channelmixerrgb.c

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/*
  This file is part of the Ansel project.
  Copyright (C) 2020-2023, 2025-2026 Aurélien PIERRE.
  Copyright (C) 2020-2022 Chris Elston.
  Copyright (C) 2020-2022 Diederik Ter Rahe.
  Copyright (C) 2020 EdgarLux.
  Copyright (C) 2020 Harold le Clément de Saint-Marcq.
  Copyright (C) 2020 Heiko Bauke.
  Copyright (C) 2020-2021 Hubert Kowalski.
  Copyright (C) 2020-2021 Nicolas Auffray.
  Copyright (C) 2020-2022 Pascal Obry.
  Copyright (C) 2020-2021 Ralf Brown.
  Copyright (C) 2021 luzpaz.
  Copyright (C) 2021 Marco Carrarini.
  Copyright (C) 2021 Mark-64.
  Copyright (C) 2021 Olivier Samyn 🎻.
  Copyright (C) 2021 Paolo DePetrillo.
  Copyright (C) 2021 paolodepetrillo.
  Copyright (C) 2021-2022 Sakari Kapanen.
  Copyright (C) 2021-2022 Victor Forsiuk.
  Copyright (C) 2022 Aldric Renaudin.
  Copyright (C) 2022 Hanno Schwalm.
  Copyright (C) 2022 Martin Bařinka.
  Copyright (C) 2022 Philipp Lutz.
  Copyright (C) 2023-2024 Alynx Zhou.
  Copyright (C) 2023 Luca Zulberti.
  Copyright (C) 2025-2026 Guillaume Stutin.
  
  Ansel is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  Ansel is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with Ansel.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifdef HAVE_CONFIG_H
#include "caches/pixelpipe_cache_alloc.h"
#include "widgets/button.h"
#include "common/conf.h"
#include "config.h"
#endif
#include "widgets/bauhaus.h"
#include "common/paths.h"   // DT_PATH_MAX
#include "widgets/collapsible_section.h"
#include "system/macros.h"
#include "system/openmp.h"
#include "system/target_clones.h"
#include "system/mem_alloc.h"
#include "system/simd.h"
#include "common/logging.h"
#include "common/module_versioning.h"
#include "math/homography.h"
#include "pixel/chromatic_adaptation.h"
#include "common/colorspaces_inline_conversions.h"
#include "common/colorchecker.h"
#include "math/matrices.h"
#include "common/file_location.h"
#include "pixel/illuminants.h"
#include "common/imagebuf.h"
#include "develop/dev_roi_request.h"
#include "develop/iop_profile.h"
#include "common/opencl.h"
#include "control/control.h"
#include "develop/imageop_gui.h"
#include "math/openmp_maths.h"
#include "math/gaussian_elimination.h"
#include "gui/color_picker_proxy.h"
#include "gui/presets.h"
#include "iop/channelmixerrgb_shared.h"
#include "iop/iop_api.h"
 
// The shared implementation is its own translation unit, compiled once and linked
// into the single IOP object set. It used to be textually included here, once per
// consuming module, because two shared objects could not each carry a copy of its
// globals; with the modules linked statically there is exactly one link and one copy.
 
#include <assert.h>
#include <float.h>
#include <gtk/gtk.h>
#include <glib.h>
#include <inttypes.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "widgets/label.h"
#include "widgets/notebook.h"
#include "gui/screen_metrics.h"
#include "control/signal.h"
 
DT_MODULE_INTROSPECTION(3, dt_iop_channelmixer_rgb_params_t)
 
#define CHANNEL_SIZE 4
#define INVERSE_SQRT_3 0.5773502691896258f
#define COLOR_MIN -2.0
#define COLOR_MAX 2.0
#define ILLUM_X_MAX 360.0
#define ILLUM_Y_MAX 300.0
#define LIGHTNESS_MAX 100.0
#define HUE_MAX 360.0
#define CHROMA_MAX 128.0
#define TEMP_MIN 1667.
#define TEMP_MAX 25000.
#define DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF "plugins/darkroom/channelmixerrgb/mixer_mode"
#define DT_CHANNELMIXERRGB_SIMPLE_TAN_SCALE DT_IOP_CHANNELMIXER_SHARED_SIMPLE_TAN_SCALE
#define DT_CHANNELMIXERRGB_SIMPLE_EPS DT_IOP_CHANNELMIXER_SHARED_SIMPLE_EPS
#define DT_CHANNELMIXERRGB_SIMPLE_CHROMA_PROBE DT_IOP_CHANNELMIXER_SHARED_SIMPLE_CHROMA_PROBE
 
typedef enum dt_iop_channelmixer_rgb_version_t
{
  CHANNELMIXERRGB_V_1 = 0, // $DESCRIPTION: "version 1 (2020)"
  CHANNELMIXERRGB_V_2 = 1, // $DESCRIPTION: "version 2 (2021)"
  CHANNELMIXERRGB_V_3 = 2, // $DESCRIPTION: "version 3 (Apr 2021)"
} dt_iop_channelmixer_rgb_version_t;
 
typedef struct dt_iop_channelmixer_rgb_params_t
{
  /* params of v1 and v2 */
  float red[CHANNEL_SIZE];         // $MIN: COLOR_MIN $MAX: COLOR_MAX
  float green[CHANNEL_SIZE];       // $MIN: COLOR_MIN $MAX: COLOR_MAX
  float blue[CHANNEL_SIZE];        // $MIN: COLOR_MIN $MAX: COLOR_MAX
  float saturation[CHANNEL_SIZE];  // $MIN: -1.0 $MAX: 1.0
  float lightness[CHANNEL_SIZE];   // $MIN: -1.0 $MAX: 1.0
  float grey[CHANNEL_SIZE];        // $MIN: -2.0 $MAX: 2.0
  gboolean normalize_R, normalize_G, normalize_B, normalize_sat, normalize_light, normalize_grey; // $DESCRIPTION: "normalize channels"
  dt_illuminant_t illuminant;      // $DEFAULT: DT_ILLUMINANT_D
  dt_illuminant_fluo_t illum_fluo; // $DEFAULT: DT_ILLUMINANT_FLUO_F3 $DESCRIPTION: "F source"
  dt_illuminant_led_t illum_led;   // $DEFAULT: DT_ILLUMINANT_LED_B5 $DESCRIPTION: "LED source"
  dt_adaptation_t adaptation;      // $DEFAULT: DT_ADAPTATION_CAT16
  float x, y;                      // $DEFAULT: 0.333
  float temperature;               // $MIN: TEMP_MIN $MAX: TEMP_MAX $DEFAULT: 5003.
  float gamut;                     // $MIN: 0.0 $MAX: 12.0 $DEFAULT: 1.0 $DESCRIPTION: "gamut compression"
  gboolean clip;                   // $DEFAULT: TRUE $DESCRIPTION: "clip negative RGB from gamut"
 
  /* params of v3 */
  dt_iop_channelmixer_rgb_version_t version; // $DEFAULT: CHANNELMIXERRGB_V_3 $DESCRIPTION: "saturation algorithm"
 
  /* always add new params after this so we can import legacy params with memcpy on the common part of the struct */
 
} dt_iop_channelmixer_rgb_params_t;
 
 
typedef enum dt_solving_strategy_t
{
  DT_SOLVE_OPTIMIZE_NONE = 0,
  DT_SOLVE_OPTIMIZE_LOW_SAT = 1,
  DT_SOLVE_OPTIMIZE_HIGH_SAT = 2,
  DT_SOLVE_OPTIMIZE_SKIN = 3,
  DT_SOLVE_OPTIMIZE_FOLIAGE = 4,
  DT_SOLVE_OPTIMIZE_SKY = 5,
  DT_SOLVE_OPTIMIZE_AVG_DELTA_E = 6,
  DT_SOLVE_OPTIMIZE_MAX_DELTA_E = 7,
} dt_solving_strategy_t;
 
 
typedef enum dt_spot_mode_t
{
  DT_SPOT_MODE_CORRECT = 0,
  DT_SPOT_MODE_MEASURE = 1,
  DT_SPOT_MODE_LAST
} dt_spot_mode_t;
 
typedef enum dt_iop_channelmixer_rgb_mixer_mode_t
{
  DT_CHANNELMIXERRGB_MIXER_COMPLETE = 0,
  DT_CHANNELMIXERRGB_MIXER_SIMPLE = 1,
  DT_CHANNELMIXERRGB_MIXER_PRIMARIES = 2,
  DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING = 3,
} dt_iop_channelmixer_rgb_mixer_mode_t;
 
typedef dt_iop_channelmixer_shared_simple_probe_t dt_iop_channelmixer_rgb_simple_probe_t;
typedef dt_iop_channelmixer_shared_primaries_basis_t dt_iop_channelmixer_rgb_primaries_basis_t;
typedef dt_iop_channelmixer_shared_simple_params_t dt_iop_channelmixer_rgb_simple_params_t;
typedef dt_iop_channelmixer_shared_primaries_params_t dt_iop_channelmixer_rgb_primaries_params_t;
typedef dt_iop_channelmixer_shared_white_preserving_params_t dt_iop_channelmixer_rgb_white_preserving_params_t;
 
#define DT_CHANNELMIXERRGB_SIMPLE_PROBE_ROTATION DT_IOP_CHANNELMIXER_SHARED_SIMPLE_PROBE_ROTATION
#define DT_CHANNELMIXERRGB_SIMPLE_PROBE_AXIS_1 DT_IOP_CHANNELMIXER_SHARED_SIMPLE_PROBE_AXIS_1
#define DT_CHANNELMIXERRGB_SIMPLE_PROBE_AXIS_2 DT_IOP_CHANNELMIXER_SHARED_SIMPLE_PROBE_AXIS_2
#define DT_CHANNELMIXERRGB_PRIMARIES_BASIS_RGB DT_IOP_CHANNELMIXER_SHARED_PRIMARIES_BASIS_RGB
#define DT_CHANNELMIXERRGB_PRIMARIES_BASIS_XYZ DT_IOP_CHANNELMIXER_SHARED_PRIMARIES_BASIS_XYZ
#define DT_CHANNELMIXERRGB_PRIMARIES_BASIS_BRADFORD DT_IOP_CHANNELMIXER_SHARED_PRIMARIES_BASIS_BRADFORD
#define DT_CHANNELMIXERRGB_PRIMARIES_BASIS_CAT16 DT_IOP_CHANNELMIXER_SHARED_PRIMARIES_BASIS_CAT16
 
typedef struct dt_iop_channelmixer_rgb_gui_data_t
{
  GtkNotebook *notebook;
  GtkWidget *mixer_mode, *mixer_stack;
  GtkWidget *simple_theta, *simple_psi, *simple_stretch_1, *simple_stretch_2, *simple_coupling_1, *simple_coupling_2;
  GtkWidget *primaries_achromatic_hue, *primaries_achromatic_purity, *primaries_red_hue, *primaries_red_purity;
  GtkWidget *primaries_green_hue, *primaries_green_purity, *primaries_blue_hue, *primaries_blue_purity, *primaries_gain;
  GtkWidget *white_preserving_red_rotation, *white_preserving_red_saturation;
  GtkWidget *white_preserving_green_rotation, *white_preserving_green_saturation;
  GtkWidget *white_preserving_blue_rotation, *white_preserving_blue_saturation;
  GtkWidget *illuminant, *temperature, *adaptation, *gamut, *clip;
  GtkWidget *illum_fluo, *illum_led, *illum_x, *illum_y, *approx_cct, *illum_color;
  GtkWidget *scale_red_R, *scale_red_G, *scale_red_B;
  GtkWidget *scale_green_R, *scale_green_G, *scale_green_B;
  GtkWidget *scale_blue_R, *scale_blue_G, *scale_blue_B;
  GtkWidget *scale_saturation_R, *scale_saturation_G, *scale_saturation_B, *saturation_version;
  GtkWidget *scale_lightness_R, *scale_lightness_G, *scale_lightness_B;
  GtkWidget *scale_grey_R, *scale_grey_G, *scale_grey_B;
  GtkWidget *normalize_R, *normalize_G, *normalize_B, *normalize_sat, *normalize_light, *normalize_grey;
  GtkWidget *color_picker;
  float xy[2];
  float XYZ[4];
 
  point_t box[4];           // the current coordinates, possibly non rectangle, of the bounding box for the color checker
  point_t ideal_box[4];     // the desired coordinates of the perfect rectangle bounding box for the color checker
  point_t center_box;       // the barycenter of both boxes
  gboolean active_node[4];  // true if the cursor is close to a node (node = corner of the bounding box)
  gboolean is_cursor_close; // do we have the cursor close to a node ?
  gboolean drag_drop;       // are we currently dragging and dropping a node ?
  point_t click_start;      // the coordinates where the drag and drop started
  point_t click_end;        // the coordinates where the drag and drop started
  dt_color_checker_t *checker;
  dt_solving_strategy_t optimization;
  float safety_margin;
 
  float homography[9];          // the perspective correction matrix
  float inverse_homography[9];  // The inverse perspective correction matrix
  gboolean run_profile;         // order a profiling at next pipeline recompute
  gboolean run_validation;      // order a profile validation at next pipeline recompute
  gboolean profile_ready;       // notify that a profile is ready to be applied
  gboolean checker_ready;       // notify that a checker bounding box is ready to be used
  dt_colormatrix_t mix;
 
  GList *colorcheckers;
 
  GList *colorcheckers_all_color; // list of CGATS files
  GList *colorcheckers_color;    // list of CGATS files with the same number of patches as the current checker
  int n_color;
  GtkWidget *checker_msg; // message label
 
  gboolean is_profiling_started;
  GtkWidget *checkers_list, *checkers_color_list, *optimize, *safety, *label_delta_E, *button_profile, *button_validate, *button_commit;
 
  float *delta_E_in;
 
  gchar *delta_E_label_text;
 
  dt_gui_collapsible_section_t cs;
  dt_gui_collapsible_section_t csspot;
 
  GtkWidget *spot_settings, *spot_mode;
  GtkWidget *hue_spot, *chroma_spot, *lightness_spot;
  GtkWidget *origin_spot, *target_spot;
  GtkWidget *Lch_origin, *Lch_target;
  GtkWidget *use_mixing;
  dt_aligned_pixel_t spot_RGB;
} dt_iop_channelmixer_rgb_gui_data_t;
 
typedef struct dt_iop_channelmixer_rbg_data_t
{
  dt_colormatrix_t MIX;
  float DT_ALIGNED_PIXEL saturation[CHANNEL_SIZE];
  float DT_ALIGNED_PIXEL lightness[CHANNEL_SIZE];
  float DT_ALIGNED_PIXEL grey[CHANNEL_SIZE];
  dt_aligned_pixel_t illuminant; // XYZ coordinates of illuminant
  float p, gamut;
  int apply_grey;
  int clip;
  dt_adaptation_t adaptation;
  dt_illuminant_t illuminant_type;
  dt_iop_channelmixer_rgb_version_t version;
} dt_iop_channelmixer_rbg_data_t;
 
typedef struct dt_iop_channelmixer_rgb_global_data_t
{
  int kernel_channelmixer_rgb_xyz;
  int kernel_channelmixer_rgb_cat16;
  int kernel_channelmixer_rgb_bradford_full;
  int kernel_channelmixer_rgb_bradford_linear;
  int kernel_channelmixer_rgb_rgb;
} dt_iop_channelmixer_rgb_global_data_t;
 
 
void _auto_set_illuminant(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe);
static void _channelmixerrgb_set_mixer_mode(dt_iop_channelmixer_rgb_gui_data_t *g,
                                            dt_iop_channelmixer_rgb_mixer_mode_t mode);
 
const char *name()
{
  return _("color _calibration");
}
 
const char *aliases()
{
  return _("channel mixer|white balance|monochrome");
}
 
const char **description(struct dt_iop_module_t *self)
{
  return dt_iop_set_description(self, _("perform color space corrections\n"
                                        "such as white balance, channels mixing\n"
                                        "and conversions to monochrome emulating film"),
                                      _("corrective or creative"),
                                      _("linear, RGB, scene-referred"),
                                      _("linear, RGB or XYZ"),
                                      _("linear, RGB, scene-referred"));
}
 
int flags()
{
  return IOP_FLAGS_INCLUDE_IN_STYLES | IOP_FLAGS_SUPPORTS_BLENDING | IOP_FLAGS_ALLOW_TILING;
}
 
int default_group()
{
  return IOP_GROUP_COLOR;
}
 
int default_colorspace(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece)
{
  return IOP_CS_RGB;
}
 
void input_format(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece,
                  dt_iop_buffer_dsc_t *dsc)
{
  default_input_format(self, pipe, piece, dsc);
  dsc->channels = 4;
  dsc->datatype = TYPE_FLOAT;
}
 
int legacy_params(dt_iop_module_t *self, const void *const old_params, const int old_version, void *new_params,
                  const int new_version)
{
  if(old_version == 1 && new_version == 3)
  {
    // V1 and V2 use the same param structure but the normalize_grey param had no effect since commit_params
    // forced normalization no matter what. So we re-import the params and force the param to TRUE to keep edits.
    memcpy(new_params, old_params, sizeof(dt_iop_channelmixer_rgb_params_t));
    dt_iop_channelmixer_rgb_params_t *n = (dt_iop_channelmixer_rgb_params_t *)new_params;
    n->normalize_grey = TRUE;
 
    // V2 and V3 use the same param structure but these :
 
    // swap the saturation parameters for R and B to put them in natural order
    const float R = n->saturation[0];
    const float B = n->saturation[2];
    n->saturation[0] = B;
    n->saturation[2] = R;
 
    // say that these params were created with legacy code
    n->version = CHANNELMIXERRGB_V_1;
 
    return 0;
  }
  if(old_version == 2 && new_version == 3)
  {
    typedef struct dt_iop_channelmixer_rgb_params_v2_t
    {
      float red[CHANNEL_SIZE];         // $MIN: -2.0 $MAX: 2.0
      float green[CHANNEL_SIZE];       // $MIN: -2.0 $MAX: 2.0
      float blue[CHANNEL_SIZE];        // $MIN: -2.0 $MAX: 2.0
      float saturation[CHANNEL_SIZE];  // $MIN: -1.0 $MAX: 1.0
      float lightness[CHANNEL_SIZE];   // $MIN: -1.0 $MAX: 1.0
      float grey[CHANNEL_SIZE];        // $MIN: 0.0 $MAX: 1.0
      gboolean normalize_R, normalize_G, normalize_B, normalize_sat, normalize_light, normalize_grey; // $DESCRIPTION: "normalize channels"
      dt_illuminant_t illuminant;      // $DEFAULT: DT_ILLUMINANT_D
      dt_illuminant_fluo_t illum_fluo; // $DEFAULT: DT_ILLUMINANT_FLUO_F3 $DESCRIPTION: "F source"
      dt_illuminant_led_t illum_led;   // $DEFAULT: DT_ILLUMINANT_LED_B5 $DESCRIPTION: "LED source"
      dt_adaptation_t adaptation;      // $DEFAULT: DT_ADAPTATION_LINEAR_BRADFORD
      float x, y;                      // $DEFAULT: 0.333
      float temperature;               // $MIN: 1667. $MAX: 25000. $DEFAULT: 5003.
      float gamut;                     // $MIN: 0.0 $MAX: 4.0 $DEFAULT: 1.0 $DESCRIPTION: "gamut compression"
      gboolean clip;                   // $DEFAULT: TRUE $DESCRIPTION: "clip negative RGB from gamut"
    } dt_iop_channelmixer_rgb_params_v2_t;
 
    memcpy(new_params, old_params, sizeof(dt_iop_channelmixer_rgb_params_v2_t));
    dt_iop_channelmixer_rgb_params_t *n = (dt_iop_channelmixer_rgb_params_t *)new_params;
 
    // swap the saturation parameters for R and B to put them in natural order
    const float R = n->saturation[0];
    const float B = n->saturation[2];
    n->saturation[0] = B;
    n->saturation[2] = R;
 
    // say that these params were created with legacy code
    n->version = CHANNELMIXERRGB_V_1;
 
    return 0;
  }
  return 1;
}
 
void init_presets(dt_iop_module_so_t *self)
{
  dt_iop_channelmixer_rgb_params_t p;
  memset(&p, 0, sizeof(p));
 
  p.version = CHANNELMIXERRGB_V_3;
 
  // bypass adaptation
  p.illuminant = DT_ILLUMINANT_PIPE;
  p.adaptation = DT_ADAPTATION_XYZ;
 
  // set everything to no-op
  p.gamut = 0.f;
  p.clip = FALSE;
  p.illum_fluo = DT_ILLUMINANT_FLUO_F3;
  p.illum_led = DT_ILLUMINANT_LED_B5;
  p.temperature = 5003.f;
  illuminant_to_xy(DT_ILLUMINANT_PIPE, NULL, NULL, &p.x, &p.y, p.temperature, DT_ILLUMINANT_FLUO_LAST, DT_ILLUMINANT_LED_LAST);
 
  p.red[0] = 1.f;
  p.red[1] = 0.f;
  p.red[2] = 0.f;
  p.green[0] = 0.f;
  p.green[1] = 1.f;
  p.green[2] = 0.f;
  p.blue[0] = 0.f;
  p.blue[1] = 0.f;
  p.blue[2] = 1.f;
 
  p.saturation[0] = 0.f;
  p.saturation[1] = 0.f;
  p.saturation[2] = 0.f;
  p.lightness[0] = 0.f;
  p.lightness[1] = 0.f;
  p.lightness[2] = 0.f;
  p.grey[0] = 0.f;
  p.grey[1] = 0.f;
  p.grey[2] = 0.f;
 
  p.normalize_R = TRUE;
  p.normalize_G = TRUE;
  p.normalize_B = TRUE;
  p.normalize_sat = FALSE;
  p.normalize_light = FALSE;
  p.normalize_grey = TRUE;
 
  // Create B&W presets
  p.clip = TRUE;
  p.grey[0] = 0.f;
  p.grey[1] = 1.f;
  p.grey[2] = 0.f;
 
  dt_gui_presets_add_generic(_("B&W: luminance-based"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // film emulations
 
  /* These emulations are built using spectral sensitivies provided by film manufacturers for tungsten light,
  * corrected in spectral domain for D50 illuminant, and integrated in spectral space against CIE 2° 1931 XYZ
  * color matching functions in the Python lib Colour, with the following code :
  *
    import colour
    import numpy as np
 
    XYZ = np.zeros((3))
 
    for l in range(360, 830):
        XYZ += film_CMF[l] * colour.colorimetry.STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'][l] / colour.ILLUMINANTS_SDS['A'][l] * colour.ILLUMINANTS_SDS['D50'][l]
 
    XYZ / np.sum(XYZ)
  *
  * The film CMF is visually approximated from the graph. It is still more accurate than bullshit factors
  * in legacy channel mixer that don't even say in which RGB space they are supposed to be applied.
  */
 
  // ILFORD HP5 +
  // https://www.ilfordphoto.com/amfile/file/download/file/1903/product/695/
  p.grey[0] = 0.25304098f;
  p.grey[1] = 0.25958747f;
  p.grey[2] = 0.48737156f;
 
  dt_gui_presets_add_generic(_("B&W: ILFORD HP5+"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // ILFORD Delta 100
  // https://www.ilfordphoto.com/amfile/file/download/file/3/product/681/
  p.grey[0] = 0.24552374f;
  p.grey[1] = 0.25366007f;
  p.grey[2] = 0.50081619f;
 
  dt_gui_presets_add_generic(_("B&W: ILFORD DELTA 100"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // ILFORD Delta 400 and 3200 - they have the same curve
  // https://www.ilfordphoto.com/amfile/file/download/file/1915/product/685/
  // https://www.ilfordphoto.com/amfile/file/download/file/1913/product/683/
  p.grey[0] = 0.24376712f;
  p.grey[1] = 0.23613559f;
  p.grey[2] = 0.52009729f;
 
  dt_gui_presets_add_generic(_("B&W: ILFORD DELTA 400 - 3200"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // ILFORD FP4+
  // https://www.ilfordphoto.com/amfile/file/download/file/1919/product/690/
  p.grey[0] = 0.24149085f;
  p.grey[1] = 0.22149272f;
  p.grey[2] = 0.53701643f;
 
  dt_gui_presets_add_generic(_("B&W: ILFORD FP4+"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // Fuji Acros 100
  // https://dacnard.wordpress.com/2013/02/15/the-real-shades-of-gray-bw-film-is-a-matter-of-heart-pt-1/
  p.grey[0] = 0.333f;
  p.grey[1] = 0.313f;
  p.grey[2] = 0.353f;
 
  dt_gui_presets_add_generic(_("B&W: Fuji Acros 100"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // Kodak ?
  // can't find spectral sensitivity curves and the illuminant under which they are produced,
  // so ¯\_(ツ)_/¯
 
  // basic channel-mixer
  p.adaptation = DT_ADAPTATION_RGB; // bypass adaptation
  p.grey[0] = 0.f;
  p.grey[1] = 0.f;
  p.grey[2] = 0.f;
  p.normalize_R = TRUE;
  p.normalize_G = TRUE;
  p.normalize_B = TRUE;
  p.normalize_grey = FALSE;
  p.clip = FALSE;
  dt_gui_presets_add_generic(_("basic channel mixer"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // swap G-B
  p.red[0] = 1.f;
  p.red[1] = 0.f;
  p.red[2] = 0.f;
  p.green[0] = 0.f;
  p.green[1] = 0.f;
  p.green[2] = 1.f;
  p.blue[0] = 0.f;
  p.blue[1] = 1.f;
  p.blue[2] = 0.f;
  dt_gui_presets_add_generic(_("swap G and B"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // swap G-R
  p.red[0] = 0.f;
  p.red[1] = 1.f;
  p.red[2] = 0.f;
  p.green[0] = 1.f;
  p.green[1] = 0.f;
  p.green[2] = 0.f;
  p.blue[0] = 0.f;
  p.blue[1] = 0.f;
  p.blue[2] = 1.f;
  dt_gui_presets_add_generic(_("swap G and R"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // swap R-B
  p.red[0] = 0.f;
  p.red[1] = 0.f;
  p.red[2] = 1.f;
  p.green[0] = 0.f;
  p.green[1] = 1.f;
  p.green[2] = 0.f;
  p.blue[0] = 1.f;
  p.blue[1] = 0.f;
  p.blue[2] = 0.f;
  dt_gui_presets_add_generic(_("swap R and B"), self->op,
                             self->version(), &p, sizeof(p), 1);
}
 
 
// Core: compute the CAT adaptation ratio between the camera matrix's bogus-D65 and the given white
// balance multipliers `wb_coeffs`. The coeff SOURCE differs by caller thread, and that is the whole
// point of splitting this out: the pipeline must read temperature's coeffs from the per-piece buffer
// descriptor (piece->dsc_in.temperature.coeffs, propagated in pipe order), NEVER from dev->proxy
// (a GUI/main-thread inter-module channel). The GUI wrapper get_white_balance_coeff() sources proxy.
__DT_CLONE_TARGETS__
static int _custom_wb_from_coeffs(struct dt_iop_module_t *self, const dt_aligned_pixel_t wb_coeffs,
                                  dt_aligned_pixel_t custom_wb)
{
  // Init output with a no-op
  for(size_t k = 0; k < 4; k++) custom_wb[k] = 1.f;
 
  if(!dt_image_is_matrix_correction_supported(&self->dev->image_storage))
  {
    dt_iop_fmt_log(self, "get_white_balance_coeff: class=%s matrix_supported=0 -> custom_wb=no-op (CAT uses identity)",
                   dt_image_pipe_class_name(dt_image_pipe_class(&self->dev->image_storage)));
    return 1;
  }
 
  // First, get the D65-ish coeffs from the input matrix
  // keep this in synch with calculate_bogus_daylight_wb from temperature.c !
  // predicts the bogus D65 that temperature.c will compute for the camera input matrix
  double bwb[4];
 
  if(dt_colorspaces_conversion_matrices_rgb(&self->dev->image_storage.adobe_XYZ_to_CAM[0][0],
                                            NULL, NULL,
                                            self->dev->image_storage.d65_color_matrix, bwb))
  {
    // normalize green:
    const double green = bwb[1];
    bwb[0] /= green;
    bwb[2] /= green;
    bwb[1] = 1.0;
    // bwb[3] is the SECOND green. For non-4-colour sensors the matrix's 4th coefficient is bogus
    // (often huge or inf, see the temperature.c "usually NAN for RGB" note): both green sites
    // share the first green, so force it to the green reference instead of propagating garbage.
    bwb[3] = (self->dev->image_storage.flags & DT_IMAGE_4BAYER) ? bwb[3] / green : 1.0;
  }
  else
  {
    return 1;
  }
 
  // Second, if the temperature module is not using these, for example because they are wrong
  // and user made a correct preset, find the WB adaptation ratio
  if(wb_coeffs[0] != 0.f)
  {
    for(size_t k = 0; k < 4; k++)
    {
      // Guard the second-green ratio: wb_coeffs[3] may be 0 (non-RGBG sensor), which would
      // yield inf. Mirror the first-green ratio in that case so custom_wb stays finite.
      const float denom = wb_coeffs[k];
      custom_wb[k] = (k == 3 && !isnormal(denom)) ? custom_wb[1] : bwb[k] / denom;
    }
  }
 
  return 0;
}
 
// GUI-thread wrapper: source temperature's WB from the dev proxy (the GUI inter-module channel).
// Pipeline code must NOT call this -- use _custom_wb_from_coeffs(self, piece->dsc_in.temperature.coeffs, ...).
__DT_CLONE_TARGETS__
static int get_white_balance_coeff(struct dt_iop_module_t *self, dt_aligned_pixel_t custom_wb)
{
  return _custom_wb_from_coeffs(self, self->dev->proxy.wb_coeffs, custom_wb);
}
 
 
static inline __attribute__((always_inline)) dt_aligned_pixel_simd_t
gamut_mapping(const dt_aligned_pixel_simd_t input, const float compression, const int clip)
{
  // Get the sum XYZ
  const float sum = input[0] + input[1] + input[2];
  const float Y = input[1];
 
  if(sum > 0.f && Y > 0.f)
  {
    // Convert to xyY
    float x = input[0] / sum;
    float y = input[1] / sum;
 
    // Convert to uvY
    const float uv_denominator = -2.f * x + 12.f * y + 3.f;
    float u = 4.f * x / uv_denominator;
    float v = 9.f * y / uv_denominator;
 
    // Get the chromaticity difference with white point uv
    const float D50[2] DT_ALIGNED_PIXEL = { 0.20915914598542354f, 0.488075320769787f };
    const float delta[2] DT_ALIGNED_PIXEL = { D50[0] - u, D50[1] - v };
    const float Delta = Y * (sqf(delta[0]) + sqf(delta[1]));
 
    // Compress chromaticity (move toward white point)
    const float correction = (compression == 0.0f) ? 0.f : powf(Delta, compression);
    // Ensure the correction does not bring our uyY vector the other side of D50
    // that would switch to the opposite color, so we clip at D50
    const float tmp_u = DT_FMA(correction, delta[0], u);
    const float tmp_v = DT_FMA(correction, delta[1], v);
    u = (u > D50[0]) ? fmaxf(tmp_u, D50[0]) : fminf(tmp_u, D50[0]);
    v = (v > D50[1]) ? fmaxf(tmp_v, D50[1]) : fminf(tmp_v, D50[1]);
 
    // Convert back to xyY
    const float xy_denominator = 6.f * u - 16.f * v + 12.f;
    x = 9.f * u / xy_denominator;
    y = 4.f * v / xy_denominator;
 
    // Clip upon request
    if(clip)
    {
      x = fmaxf(x, 0.0f);
      y = fmaxf(y, 0.0f);
    }
 
    // Check sanity of y
    // since we later divide by y, it can't be zero
    y = fmaxf(y, NORM_MIN);
 
    // Check sanity of x and y :
    // since Z = Y (1 - x - y) / y, if x + y >= 1, Z will be negative
    const float scale = x + y;
    const int sanitize = (scale >= 1.f);
    if(sanitize)
    {
      x /= scale;
      y /= scale;
    }
 
    return (dt_aligned_pixel_simd_t){ Y * x / y, Y, Y * (1.f - x - y) / y, 0.f };
  }
  else
  {
    // sum of channels == 0, and/or Y == 0 so we have black
    return (dt_aligned_pixel_simd_t){ 0.f };
  }
}
__OMP_DECLARE_SIMD__(aligned(input, saturation, lightness, output:16) uniform(version))
static inline __attribute__((always_inline)) void
luma_chroma(const dt_aligned_pixel_t input, const dt_aligned_pixel_t saturation,
            const dt_aligned_pixel_t lightness, dt_aligned_pixel_t output,
            const dt_iop_channelmixer_rgb_version_t version)
{
  // Compute euclidean norm
  float norm = euclidean_norm(input);
  const float avg = fmaxf((input[0] + input[1] + input[2]) / 3.0f, NORM_MIN);
 
  if(norm > 0.f && avg > 0.f)
  {
    // Compute flat lightness adjustment
    const float mix = scalar_product(input, lightness);
 
    // Compensate the norm to get color ratios (R, G, B) = (1, 1, 1) for grey (colorless) pixels.
    if(version == CHANNELMIXERRGB_V_3) norm *= INVERSE_SQRT_3;
 
    // Ratios
    for(size_t c = 0; c < 3; c++) output[c] = input[c] / norm;
 
    // Compute ratios and a flat colorfulness adjustment for the whole pixel
    float coeff_ratio = 0.f;
 
    if(version == CHANNELMIXERRGB_V_1)
    {
      for(size_t c = 0; c < 3; c++)
        coeff_ratio += sqf(1.0f - output[c]) * saturation[c];
    }
    else
      coeff_ratio = scalar_product(output, saturation) / 3.f;
 
    // Adjust the RGB ratios with the pixel correction
    for(size_t c = 0; c < 3; c++)
    {
      // if the ratio was already invalid (negative), we accept the result to be invalid too
      // otherwise bright saturated blues end up solid black
      const float min_ratio = (output[c] < 0.0f) ? output[c] : 0.0f;
      const float output_inverse = 1.0f - output[c];
      output[c] = fmaxf(DT_FMA(output_inverse, coeff_ratio, output[c]),
                        min_ratio); // output_inverse  * coeff_ratio + output
    }
 
    // The above interpolation between original pixel ratios and (1, 1, 1) might change the norm of the
    // ratios. Compensate for that.
    if(version == CHANNELMIXERRGB_V_3) norm /= euclidean_norm(output) * INVERSE_SQRT_3;
 
    // Apply colorfulness adjustment channel-wise and repack with lightness to get LMS back
    norm *= fmaxf(1.f + mix / avg, 0.f);
    for(size_t c = 0; c < 3; c++) output[c] *= norm;
  }
  else
  {
    // we have black, 0 stays 0, no luminance = no color
    for(size_t c = 0; c < 3; c++) output[c] = input[c];
  }
}
 
__DT_CLONE_TARGETS__
static inline void loop_switch(const float *const restrict in, float *const restrict out,
                               const size_t width, const size_t height, const size_t ch,
                               const dt_colormatrix_t XYZ_to_RGB, const dt_colormatrix_t RGB_to_XYZ,
                               const dt_colormatrix_t MIX, const dt_aligned_pixel_t illuminant,
                               const dt_aligned_pixel_t saturation, const dt_aligned_pixel_t lightness,
                               const dt_aligned_pixel_t grey, const float p, const float gamut,
                               const int clip, const int apply_grey, const dt_adaptation_t kind,
                               const dt_iop_channelmixer_rgb_version_t version)
{
  dt_colormatrix_t RGB_to_XYZ_t;
  dt_colormatrix_t XYZ_to_RGB_t;
  dt_colormatrix_t MIX_t;
  transpose_3xSSE(RGB_to_XYZ, RGB_to_XYZ_t);
  transpose_3xSSE(XYZ_to_RGB, XYZ_to_RGB_t);
  transpose_3xSSE(MIX, MIX_t);
  const dt_aligned_pixel_simd_t rgb_to_xyz0 = dt_colormatrix_row_to_simd(RGB_to_XYZ_t, 0);
  const dt_aligned_pixel_simd_t rgb_to_xyz1 = dt_colormatrix_row_to_simd(RGB_to_XYZ_t, 1);
  const dt_aligned_pixel_simd_t rgb_to_xyz2 = dt_colormatrix_row_to_simd(RGB_to_XYZ_t, 2);
  const dt_aligned_pixel_simd_t xyz_to_rgb0 = dt_colormatrix_row_to_simd(XYZ_to_RGB_t, 0);
  const dt_aligned_pixel_simd_t xyz_to_rgb1 = dt_colormatrix_row_to_simd(XYZ_to_RGB_t, 1);
  const dt_aligned_pixel_simd_t xyz_to_rgb2 = dt_colormatrix_row_to_simd(XYZ_to_RGB_t, 2);
  const dt_aligned_pixel_simd_t mix0 = dt_colormatrix_row_to_simd(MIX_t, 0);
  const dt_aligned_pixel_simd_t mix1 = dt_colormatrix_row_to_simd(MIX_t, 1);
  const dt_aligned_pixel_simd_t mix2 = dt_colormatrix_row_to_simd(MIX_t, 2);
  const dt_aligned_pixel_simd_t illuminant_v = dt_load_simd_aligned(illuminant);
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < height * width * 4; k += 4)
  {
    const dt_aligned_pixel_simd_t in_v = dt_load_simd_aligned(in + k);
    dt_aligned_pixel_simd_t temp_one_v = { 0.f };
    dt_aligned_pixel_simd_t temp_two_v = clip ? dt_simd_max_zero(in_v) : in_v;
 
    /* WE START IN PIPELINE RGB */
 
    switch(kind)
    {
      case DT_ADAPTATION_FULL_BRADFORD:
      {
        // Convert from RGB to XYZ
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
        const float Y = temp_one_v[1];
 
        // Convert to LMS
        temp_two_v = _downscale_vector_simd(convert_XYZ_to_bradford_LMS(temp_one_v), Y);
        // Do white balance
        temp_one_v = _upscale_vector_simd(bradford_adapt_D50(temp_two_v, illuminant_v, p, TRUE), Y);
        // Compute the 3D mix - this is a rotation + homothety of the vector base
        temp_two_v = dt_mat3x4_mul_vec4(temp_one_v, mix0, mix1, mix2);
        temp_one_v = convert_bradford_LMS_to_XYZ(temp_two_v);
 
        break;
      }
      case DT_ADAPTATION_LINEAR_BRADFORD:
      {
        // Convert from RGB to XYZ
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
        const float Y = temp_one_v[1];
 
        // Convert to LMS
        temp_two_v = _downscale_vector_simd(convert_XYZ_to_bradford_LMS(temp_one_v), Y);
        // Do white balance
        temp_one_v = _upscale_vector_simd(bradford_adapt_D50(temp_two_v, illuminant_v, p, FALSE), Y);
        // Compute the 3D mix - this is a rotation + homothety of the vector base
        temp_two_v = dt_mat3x4_mul_vec4(temp_one_v, mix0, mix1, mix2);
        temp_one_v = convert_bradford_LMS_to_XYZ(temp_two_v);
 
        break;
      }
      case DT_ADAPTATION_CAT16:
      {
        // Convert from RGB to XYZ
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
        const float Y = temp_one_v[1];
 
        // Convert to LMS
        temp_two_v = _downscale_vector_simd(convert_XYZ_to_CAT16_LMS(temp_one_v), Y);
        // Do white balance
        temp_one_v = _upscale_vector_simd(CAT16_adapt_D50(temp_two_v, illuminant_v, 1.0f, TRUE), Y);
        // Compute the 3D mix - this is a rotation + homothety of the vector base
        temp_two_v = dt_mat3x4_mul_vec4(temp_one_v, mix0, mix1, mix2);
        temp_one_v = convert_CAT16_LMS_to_XYZ(temp_two_v);
 
        break;
      }
      case DT_ADAPTATION_XYZ:
      {
        // Convert from RGB to XYZ
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
        const float Y = temp_one_v[1];
 
        // Do white balance in XYZ
        temp_two_v = _upscale_vector_simd(XYZ_adapt_D50(_downscale_vector_simd(temp_one_v, Y), illuminant_v), Y);
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, mix0, mix1, mix2);
 
        break;
      }
      case DT_ADAPTATION_RGB:
      case DT_ADAPTATION_LAST:
      default:
      {
        // No white balance.
 
        // Compute the 3D mix in RGB - this is a rotation + homothety of the vector base
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, mix0, mix1, mix2);
        temp_one_v = dt_mat3x4_mul_vec4(temp_one_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
        break;
      }
    }
 
    /* FROM HERE WE ARE MANDATORILY IN XYZ - DATA IS IN temp_one */
 
    // Gamut mapping happens in XYZ space no matter what
    temp_two_v = gamut_mapping(temp_one_v, gamut, clip);
 
    // convert to LMS, XYZ or pipeline RGB
    switch(kind)
    {
      case DT_ADAPTATION_FULL_BRADFORD:
      case DT_ADAPTATION_LINEAR_BRADFORD:
      case DT_ADAPTATION_CAT16:
      case DT_ADAPTATION_XYZ:
      {
        temp_one_v = convert_any_XYZ_to_LMS(temp_two_v, kind);
        break;
      }
      case DT_ADAPTATION_RGB:
      case DT_ADAPTATION_LAST:
      default:
      {
        // Convert from XYZ to RGB
        temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, xyz_to_rgb0, xyz_to_rgb1, xyz_to_rgb2);
        break;
      }
    }
 
    /* FROM HERE WE ARE IN LMS, XYZ OR PIPELINE RGB depending on user param - DATA IS IN temp_one */
 
    // Clip in LMS
    if(clip) temp_one_v = dt_simd_max_zero(temp_one_v);
 
    // Apply lightness / saturation adjustment
    dt_aligned_pixel_t luma_input;
    dt_aligned_pixel_t luma_output;
    dt_store_simd_aligned(luma_input, temp_one_v);
    luma_chroma(luma_input, saturation, lightness, luma_output, version);
    temp_two_v = dt_load_simd_aligned(luma_output);
 
    // Clip in LMS
    if(clip) temp_two_v = dt_simd_max_zero(temp_two_v);
 
    // Save
    if(apply_grey)
    {
      // Turn LMS, XYZ or pipeline RGB into monochrome
      const float grey_mix = fmaxf(temp_two_v[0] * grey[0] + temp_two_v[1] * grey[1] + temp_two_v[2] * grey[2], 0.0f);
      dt_store_simd_nontemporal(out + k, (dt_aligned_pixel_simd_t){ grey_mix, grey_mix, grey_mix, in_v[3] });
    }
    else
    {
      // Convert back to XYZ
      switch(kind)
      {
        case DT_ADAPTATION_FULL_BRADFORD:
        case DT_ADAPTATION_LINEAR_BRADFORD:
        case DT_ADAPTATION_CAT16:
        case DT_ADAPTATION_XYZ:
        {
          temp_one_v = convert_any_LMS_to_XYZ(temp_two_v, kind);
          break;
        }
        case DT_ADAPTATION_RGB:
        case DT_ADAPTATION_LAST:
        default:
        {
          // Convert from RBG to XYZ
          temp_one_v = dt_mat3x4_mul_vec4(temp_two_v, rgb_to_xyz0, rgb_to_xyz1, rgb_to_xyz2);
          break;
        }
      }
 
      /* FROM HERE WE ARE MANDATORILY IN XYZ - DATA IS IN temp_one */
 
      // Clip in XYZ
      if(clip) temp_one_v = dt_simd_max_zero(temp_one_v);
 
      // Convert back to RGB
      temp_two_v = dt_mat3x4_mul_vec4(temp_one_v, xyz_to_rgb0, xyz_to_rgb1, xyz_to_rgb2);
      if(clip) temp_two_v = dt_simd_max_zero(temp_two_v);
 
      dt_store_simd_nontemporal(out + k, (dt_aligned_pixel_simd_t){ temp_two_v[0], temp_two_v[1], temp_two_v[2], in_v[3] });
    }
  }
  dt_omploop_sfence();  // ensure that nontemporal writes complete before we attempt to read output
}
 
// util to shift pixel index without headache
#define SHF(ii, jj, c) ((i + ii) * width + j + jj) * ch + c
#define OFF 4
 
__DT_CLONE_TARGETS__
static inline int auto_detect_WB(const float *const restrict in, dt_illuminant_t illuminant,
                                 const size_t width, const size_t height, const size_t ch,
                                 const dt_colormatrix_t RGB_to_XYZ, dt_aligned_pixel_t xyz)
{
   float *const restrict temp = dt_pixelpipe_cache_alloc_align_float_cache(width * height * ch, 0);
   if(IS_NULL_PTR(temp)) return 1;
 
   // Convert RGB to xy
  __OMP_PARALLEL_FOR__(collapse(2) )
  for(size_t i = 0; i < height; i++)
    for(size_t j = 0; j < width; j++)
    {
      const size_t index = (i * width + j) * ch;
      dt_aligned_pixel_t RGB;
      dt_aligned_pixel_t XYZ;
 
      // Clip negatives
      for_each_channel(c,aligned(in))
        RGB[c] = fmaxf(in[index + c], 0.0f);
 
      // Convert to XYZ
      dot_product(RGB, RGB_to_XYZ, XYZ);
 
      // Convert to xyY
      const float sum = fmaxf(XYZ[0] + XYZ[1] + XYZ[2], NORM_MIN);
      XYZ[0] /= sum;   // x
      XYZ[2] = XYZ[1]; // Y
      XYZ[1] /= sum;   // y
 
      // Shift the chromaticity plane so the D50 point (target) becomes the origin
      const float D50[2] = { 0.34567f, 0.35850f };
      const float norm = dt_fast_hypotf(D50[0], D50[1]);
 
      temp[index    ] = (XYZ[0] - D50[0]) / norm;
      temp[index + 1] = (XYZ[1] - D50[1]) / norm;
      temp[index + 2] =  XYZ[2];
    }
 
  float elements = 0.f;
  dt_aligned_pixel_t xyY = { 0.f };
 
  if(illuminant == DT_ILLUMINANT_DETECT_SURFACES)
  {
    __OMP_PARALLEL_FOR__(reduction(+:xyY, elements))
    for(size_t i = 2 * OFF; i < height - 4 * OFF; i += OFF)
      for(size_t j = 2 * OFF; j < width - 4 * OFF; j += OFF)
      {
        float DT_ALIGNED_PIXEL central_average[2];
 
        for(size_t c = 0; c < 2; c++)
        {
          // B-spline local average / blur
          central_average[c] = (      temp[SHF(-OFF, -OFF, c)] + 2.f * temp[SHF(-OFF, 0, c)] +       temp[SHF(-OFF, +OFF, c)] +
                                2.f * temp[SHF(   0, -OFF, c)] + 4.f * temp[SHF(   0, 0, c)] + 2.f * temp[SHF(   0, +OFF, c)] +
                                      temp[SHF(+OFF, -OFF, c)] + 2.f * temp[SHF(+OFF, 0, c)] +       temp[SHF(+OFF, +OFF, c)]) / 16.0f;
          central_average[c] = fmaxf(central_average[c], 0.0f);
        }
 
        dt_aligned_pixel_t var = { 0.f };
 
        // compute patch-wise variance
        // If variance = 0, we are on a flat surface and want to discard that patch.
        for(size_t c = 0; c < 2; c++)
        {
          var[c] = (
                      sqf(temp[SHF(-OFF, -OFF, c)] - central_average[c]) +
                      sqf(temp[SHF(-OFF,    0, c)] - central_average[c]) +
                      sqf(temp[SHF(-OFF, +OFF, c)] - central_average[c]) +
                      sqf(temp[SHF(0,    -OFF, c)] - central_average[c]) +
                      sqf(temp[SHF(0,       0, c)] - central_average[c]) +
                      sqf(temp[SHF(0,    +OFF, c)] - central_average[c]) +
                      sqf(temp[SHF(+OFF, -OFF, c)] - central_average[c]) +
                      sqf(temp[SHF(+OFF,    0, c)] - central_average[c]) +
                      sqf(temp[SHF(+OFF, +OFF, c)] - central_average[c])
                    ) / 9.0f;
        }
 
        // Compute the patch-wise chroma covariance.
        // If covariance = 0, chroma channels are not correlated and we either have noise or chromatic aberrations.
        // Both ways, we want to discard that patch from the chroma average.
        var[2] = (
                    (temp[SHF(-OFF, -OFF, 0)] - central_average[0]) * (temp[SHF(-OFF, -OFF, 1)] - central_average[1]) +
                    (temp[SHF(-OFF,    0, 0)] - central_average[0]) * (temp[SHF(-OFF,    0, 1)] - central_average[1]) +
                    (temp[SHF(-OFF, +OFF, 0)] - central_average[0]) * (temp[SHF(-OFF, +OFF, 1)] - central_average[1]) +
                    (temp[SHF(   0, -OFF, 0)] - central_average[0]) * (temp[SHF(   0, -OFF, 1)] - central_average[1]) +
                    (temp[SHF(   0,    0, 0)] - central_average[0]) * (temp[SHF(   0,    0, 1)] - central_average[1]) +
                    (temp[SHF(   0, +OFF, 0)] - central_average[0]) * (temp[SHF(   0, +OFF, 1)] - central_average[1]) +
                    (temp[SHF(+OFF, -OFF, 0)] - central_average[0]) * (temp[SHF(+OFF, -OFF, 1)] - central_average[1]) +
                    (temp[SHF(+OFF,    0, 0)] - central_average[0]) * (temp[SHF(+OFF,    0, 1)] - central_average[1]) +
                    (temp[SHF(+OFF, +OFF, 0)] - central_average[0]) * (temp[SHF(+OFF, +OFF, 1)] - central_average[1])
                  ) / 9.0f;
 
        // Compute the Minkowski p-norm for regularization
        const float p = 8.f;
        const float p_norm
            = powf(powf(fabsf(central_average[0]), p) + powf(fabsf(central_average[1]), p), 1.f / p) + NORM_MIN;
        const float weight = var[0] * var[1] * var[2];
 
        for(size_t c = 0; c < 2; c++) xyY[c] += central_average[c] * weight / p_norm;
        elements += weight / p_norm;
      }
  }
  else if(illuminant == DT_ILLUMINANT_DETECT_EDGES)
  {
    __OMP_PARALLEL_FOR__(reduction(+:xyY, elements))
    for(size_t i = 2 * OFF; i < height - 4 * OFF; i += OFF)
      for(size_t j = 2 * OFF; j < width - 4 * OFF; j += OFF)
      {
        float DT_ALIGNED_PIXEL dd[2];
        float DT_ALIGNED_PIXEL central_average[2];
 
        for(size_t c = 0; c < 2; c++)
        {
          // B-spline local average / blur
          central_average[c] = (      temp[SHF(-OFF, -OFF, c)] + 2.f * temp[SHF(-OFF, 0, c)] +       temp[SHF(-OFF, +OFF, c)] +
                                2.f * temp[SHF(   0, -OFF, c)] + 4.f * temp[SHF(   0, 0, c)] + 2.f * temp[SHF(   0, +OFF, c)] +
                                      temp[SHF(+OFF, -OFF, c)] + 2.f * temp[SHF(+OFF, 0, c)] +       temp[SHF(+OFF, +OFF, c)]) / 16.0f;
 
          // image - blur = laplacian = edges
          dd[c] = temp[SHF(0, 0, c)] - central_average[c];
        }
 
        // Compute the Minkowski p-norm for regularization
        const float p = 8.f;
        const float p_norm = powf(powf(fabsf(dd[0]), p) + powf(fabsf(dd[1]), p), 1.f / p) + NORM_MIN;
 
        for(size_t c = 0; c < 2; c++) xyY[c] -= dd[c] / p_norm;
        elements += 1.f;
      }
  }
 
  const float D50[2] = { 0.34567f, 0.35850 };
  const float norm_D50 = dt_fast_hypotf(D50[0], D50[1]);
 
  for(size_t c = 0; c < 2; c++)
    xyz[c] = norm_D50 * (xyY[c] / elements) + D50[c];
 
  dt_pixelpipe_cache_free_align(temp);
  return 0;
}
 
__DT_CLONE_TARGETS__
static void declare_cat_on_pipe(struct dt_iop_module_t *self, gboolean preset)
{
  // Advertise to the pipeline that we are doing chromatic adaptation here
  // preset = TRUE allows to capture the CAT a priori at init time
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  if((self->enabled && !(p->adaptation == DT_ADAPTATION_RGB || p->illuminant == DT_ILLUMINANT_PIPE)) || preset)
  {
    // We do CAT here so we need to register this instance as CAT-handler.
    if(IS_NULL_PTR(self->dev->proxy.chroma_adaptation))
    {
      // We are the first to try to register, let's go !
      self->dev->proxy.chroma_adaptation = self;
    }
    else if(self->dev->proxy.chroma_adaptation == self)
    {
    }
    else
    {
      // Another instance already registered.
      // If we are lower in the pipe than it, register in its place.
      if(dt_iop_is_first_instance(self->dev->iop, self))
        self->dev->proxy.chroma_adaptation = self;
    }
  }
  else
  {
    if(!IS_NULL_PTR(self->dev->proxy.chroma_adaptation))
    {
      // We do NOT do CAT here.
      // Deregister this instance as CAT-handler if it previously registered
      if(self->dev->proxy.chroma_adaptation == self)
        self->dev->proxy.chroma_adaptation = NULL;
    }
  }
}
 
static inline gboolean _is_another_module_cat_on_pipe(struct dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g)) return FALSE;
  return self->dev->proxy.chroma_adaptation && self->dev->proxy.chroma_adaptation != self;
}
 
 
static void update_illuminants(struct dt_iop_module_t *self);
static void update_approx_cct(struct dt_iop_module_t *self);
static void update_illuminant_color(struct dt_iop_module_t *self);
 
 
static inline __attribute__((always_inline)) void check_if_close_to_daylight(const float x, const float y, float *temperature,
                                       dt_illuminant_t *illuminant, dt_adaptation_t *adaptation)
{
  /* Check if a chromaticity x, y is close to daylight within 2.5 % error margin.
   * If so, we enable the daylight GUI for better ergonomics
   * Otherwise, we default to direct x, y control for better accuracy
   *
   * Note : The use of CCT is discouraged if dE > 5 % in CIE 1960 Yuv space
   *        reference : https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470175637.ch3
   */
 
  // Get the correlated color temperature (CCT)
  float t = xy_to_CCT(x, y);
 
  // xy_to_CCT is valid only in 3000 - 25000 K. We need another model below
  if(t < 3000.f && t > 1667.f)
    t = CCT_reverse_lookup(x, y);
 
  if(!IS_NULL_PTR(temperature))
    *temperature = t;
 
  // Convert to CIE 1960 Yuv space
  float xy_ref[2] = { x, y };
  float uv_ref[2];
  xy_to_uv(xy_ref, uv_ref);
 
  float xy_test[2] = { 0.f };
  float uv_test[2];
 
  // Compute the test chromaticity from the daylight model
  illuminant_to_xy(DT_ILLUMINANT_D, NULL, NULL, &xy_test[0], &xy_test[1], t, DT_ILLUMINANT_FLUO_LAST, DT_ILLUMINANT_LED_LAST);
  xy_to_uv(xy_test, uv_test);
 
  // Compute the error between the reference illuminant and the test illuminant derivated from the CCT with daylight model
  const float delta_daylight = dt_fast_hypotf((uv_test[0] - uv_ref[0]), (uv_test[1] - uv_ref[1]));
 
  // Compute the test chromaticity from the blackbody model
  illuminant_to_xy(DT_ILLUMINANT_BB, NULL, NULL, &xy_test[0], &xy_test[1], t, DT_ILLUMINANT_FLUO_LAST, DT_ILLUMINANT_LED_LAST);
  xy_to_uv(xy_test, uv_test);
 
  // Compute the error between the reference illuminant and the test illuminant derivated from the CCT with black body model
  const float delta_bb = dt_fast_hypotf((uv_test[0] - uv_ref[0]), (uv_test[1] - uv_ref[1]));
 
  // Check the error between original and test chromaticity
  if(delta_bb < 0.005f || delta_daylight < 0.005f)
  {
    if(illuminant)
    {
      if(delta_bb < delta_daylight)
        *illuminant = DT_ILLUMINANT_BB;
      else
        *illuminant = DT_ILLUMINANT_D;
    }
  }
  else
  {
    // error is too big to use a CCT-based model, we fall back to a custom/freestyle chroma selection for the illuminant
    if(illuminant) *illuminant = DT_ILLUMINANT_CUSTOM;
  }
 
  // CAT16 is more accurate no matter the illuminant
  if(adaptation) *adaptation = DT_ADAPTATION_CAT16;
}
 
#define DEG_TO_RAD(x) (x * M_PI / 180.f)
#define RAD_TO_DEG(x) (x * 180.f / M_PI)
 
static inline void compute_patches_delta_E(const float *const restrict patches,
                                           const dt_color_checker_t *const checker,
                                           float *const restrict delta_E, float *const restrict avg_delta_E, float *const restrict max_delta_E)
{
  // Compute the delta E
 
  float dE = 0.f;
  float max_dE = 0.f;
 
  for(size_t k = 0; k < checker->patches; k++)
  {
    // Convert to Lab
    dt_aligned_pixel_t Lab_test;
    dt_aligned_pixel_t XYZ_test;
 
    // If exposure was normalized, denormalized it before
    for(size_t c = 0; c < 4; c++) XYZ_test[c] = patches[k * 4 + c];
    dt_XYZ_to_Lab(XYZ_test, Lab_test);
 
    const float *const restrict Lab_ref = checker->values[k].Lab;
 
    // Compute delta E 2000 to make your computer heat
    // ref: https://en.wikipedia.org/wiki/Color_difference#CIEDE2000
    // note : it will only be luck if I didn't mess-up the computation somewhere
    const float DL = Lab_ref[0] - Lab_test[0];
    const float L_avg = (Lab_ref[0] + Lab_test[0]) / 2.f;
    const float C_ref = dt_fast_hypotf(Lab_ref[1], Lab_ref[2]);
    const float C_test = dt_fast_hypotf(Lab_test[1], Lab_test[2]);
    const float C_avg = (C_ref + C_test) / 2.f;
    float C_avg_7 = C_avg * C_avg; // C_avg²
    C_avg_7 *= C_avg_7;            // C_avg⁴
    C_avg_7 *= C_avg_7;            // C_avg⁸
    C_avg_7 /= C_avg;              // C_avg⁷
    const float C_avg_7_ratio_sqrt = sqrtf(C_avg_7 / (C_avg_7 + 6103515625.f)); // 25⁷ = 6103515625
    const float a_ref_prime = Lab_ref[1] * (1.f + 0.5f * (1.f - C_avg_7_ratio_sqrt));
    const float a_test_prime = Lab_test[1] * (1.f + 0.5f * (1.f - C_avg_7_ratio_sqrt));
    const float C_ref_prime = dt_fast_hypotf(a_ref_prime, Lab_ref[2]);
    const float C_test_prime = dt_fast_hypotf(a_test_prime, Lab_test[2]);
    const float DC_prime = C_ref_prime - C_test_prime;
    const float C_avg_prime = (C_ref_prime + C_test_prime) / 2.f;
    float h_ref_prime = atan2f(Lab_ref[2], a_ref_prime);
    float h_test_prime = atan2f(Lab_test[2], a_test_prime);
 
    // Comply with recommendations, h = 0° where C = 0 by convention
    if(C_ref_prime == 0.f) h_ref_prime = 0.f;
    if(C_test_prime == 0.f) h_test_prime = 0.f;
 
    // Get the hue angles from [-pi ; pi] back to [0 ; 2 pi],
    // again, to comply with specifications
    if(h_ref_prime < 0.f) h_ref_prime = 2.f * M_PI - h_ref_prime;
    if(h_test_prime < 0.f) h_test_prime = 2.f * M_PI - h_test_prime;
 
    // Convert to degrees, again to comply with specs
    h_ref_prime = RAD_TO_DEG(h_ref_prime);
    h_test_prime = RAD_TO_DEG(h_test_prime);
 
    float Dh_prime = h_test_prime - h_ref_prime;
    float Dh_prime_abs = fabsf(Dh_prime);
    if(C_test_prime == 0.f || C_ref_prime == 0.f)
      Dh_prime = 0.f;
    else if(Dh_prime_abs <= 180.f)
      ;
    else if(Dh_prime_abs > 180.f && (h_test_prime <= h_ref_prime))
      Dh_prime += 360.f;
    else if(Dh_prime_abs > 180.f && (h_test_prime > h_ref_prime))
      Dh_prime -= 360.f;
 
    // update abs(Dh_prime) for later
    Dh_prime_abs = fabsf(Dh_prime);
 
    const float DH_prime = 2.f * sqrtf(C_test_prime * C_ref_prime) * sinf(DEG_TO_RAD(Dh_prime) / 2.f);
    float H_avg_prime = h_ref_prime + h_test_prime;
    if(C_test_prime == 0.f || C_ref_prime == 0.f)
      ;
    else if(Dh_prime_abs <= 180.f)
      H_avg_prime /= 2.f;
    else if(Dh_prime_abs > 180.f && (H_avg_prime < 360.f))
      H_avg_prime = (H_avg_prime + 360.f) / 2.f;
    else if(Dh_prime_abs > 180.f && (H_avg_prime >= 360.f))
      H_avg_prime = (H_avg_prime - 360.f) / 2.f;
 
    const float T = 1.f
                    - 0.17f * cosf(DEG_TO_RAD(H_avg_prime) - DEG_TO_RAD(30.f))
                    + 0.24f * cosf(2.f * DEG_TO_RAD(H_avg_prime))
                    + 0.32f * cosf(3.f * DEG_TO_RAD(H_avg_prime) + DEG_TO_RAD(6.f))
                    - 0.20f * cosf(4.f * DEG_TO_RAD(H_avg_prime) - DEG_TO_RAD(63.f));
 
    const float S_L = 1.f + (0.015f * sqf(L_avg - 50.f)) / sqrtf(20.f + sqf(L_avg - 50.f));
    const float S_C = 1.f + 0.045f * C_avg_prime;
    const float S_H = 1.f + 0.015f * C_avg_prime * T;
    const float R_T = -2.f * C_avg_7_ratio_sqrt
                      * sinf(DEG_TO_RAD(60.f) * expf(-sqf((H_avg_prime - 275.f) / 25.f)));
 
    // roll the drum, here goes the Delta E, finally...
    const float DE = sqrtf(sqf(DL / S_L) + sqf(DC_prime / S_C) + sqf(DH_prime / S_H)
                           + R_T * (DC_prime / S_C) * (DH_prime / S_H));
 
    // Delta E 1976 for reference :
    //float DE = sqrtf(sqf(Lab_test[0] - Lab_ref[0]) + sqf(Lab_test[1] - Lab_ref[1]) + sqf(Lab_test[2] - Lab_ref[2]));
 
    //fprintf(stdout, "patch %s : Lab ref \t= \t%.3f \t%.3f \t%.3f \n", checker->values[k].name, Lab_ref[0], Lab_ref[1], Lab_ref[2]);
    //fprintf(stdout, "patch %s : Lab mes \t= \t%.3f \t%.3f \t%.3f \n", checker->values[k].name, Lab_test[0], Lab_test[1], Lab_test[2]);
    //fprintf(stdout, "patch %s : dE mes \t= \t%.3f \n", checker->values[k].name, DE);
 
    delta_E[k] = DE;
    dE += DE / (float)checker->patches;
    if(DE > max_dE) max_dE = DE;
  }
 
  *avg_delta_E = dE;
  *max_delta_E = max_dE;
}
 
#define GET_WEIGHT                                                \
      float hue = atan2f(reference[2], reference[1]);             \
      const float chroma = hypotf(reference[2], reference[1]);    \
      float delta_hue = hue - ref_hue;                            \
      if(chroma == 0.f)                                           \
        delta_hue = 0.f;                                          \
      else if(fabsf(delta_hue) <= M_PI)                           \
        ;                                                         \
      else if(fabsf(delta_hue) > M_PI && (hue <= ref_hue))        \
        delta_hue += 2.f * M_PI;                                  \
      else if(fabsf(delta_hue) > M_PI && (hue > ref_hue))         \
        delta_hue -= 2.f * M_PI;                                  \
      w = sqrtf(expf(-sqf(delta_hue) / 2.f));
 
 
typedef struct {
  float black;
  float exposure;
} extraction_result_t;
 
typedef struct dt_iop_channelmixer_rgb_box_map_t
{
  float scale_x, scale_y;   // preview-request pixels -> buffer pixels
  float offset_x, offset_y; // this buffer's origin, in buffer pixels
} dt_iop_channelmixer_rgb_box_map_t;
 
 
static inline dt_iop_channelmixer_rgb_box_map_t _box_map(const dt_dev_pixelpipe_t *const pipe,
                                                         const dt_iop_roi_t *const roi)
{
  dt_iop_channelmixer_rgb_box_map_t map = { 1.f, 1.f, (float)roi->x, (float)roi->y };
  const dt_dev_roi_request_t request = dt_dev_roi_request_of_pipe(pipe);
 
  // Fall back to the identity -- i.e. the behaviour that is correct whenever the pipe does run
  // at natural_scale -- rather than scaling by a number we have no reason to trust.
  if(request.valid && request.preview_width > 0 && request.preview_height > 0)
  {
    map.scale_x = (float)roi->width / (float)request.preview_width;
    map.scale_y = (float)roi->height / (float)request.preview_height;
  }
 
  return map;
}
 
 
static inline void _map_homographies(const dt_iop_channelmixer_rgb_gui_data_t *const g,
                                     const dt_iop_channelmixer_rgb_box_map_t *const map,
                                     float forward[9], float backward[9])
{
  // apply_homography() divides rows 0 and 1 by row 2, so the translation belongs in the
  // numerators, weighted by that same row -- it is not a plain matrix addition.
  for(size_t c = 0; c < 3; c++)
  {
    forward[0 * 3 + c] = map->scale_x * g->homography[0 * 3 + c] - map->offset_x * g->homography[2 * 3 + c];
    forward[1 * 3 + c] = map->scale_y * g->homography[1 * 3 + c] - map->offset_y * g->homography[2 * 3 + c];
    forward[2 * 3 + c] = g->homography[2 * 3 + c];
  }
 
  // The backward map consumes buffer pixels, so it takes the INVERSE affine on its input.
  for(size_t r = 0; r < 3; r++)
  {
    const float column_x = g->inverse_homography[r * 3 + 0] / map->scale_x;
    const float column_y = g->inverse_homography[r * 3 + 1] / map->scale_y;
    backward[r * 3 + 0] = column_x;
    backward[r * 3 + 1] = column_y;
    backward[r * 3 + 2] = g->inverse_homography[r * 3 + 2] + column_x * map->offset_x
                                                           + column_y * map->offset_y;
  }
}
 
 
__DT_CLONE_TARGETS__
static int _extract_patches(const float *const restrict in, const dt_iop_roi_t *const roi_in,
                            dt_iop_channelmixer_rgb_gui_data_t *g,
                            const dt_iop_channelmixer_rgb_box_map_t *const box_map,
                            const dt_colormatrix_t RGB_to_XYZ, const dt_colormatrix_t XYZ_to_CAM,
                            float *const restrict patches,
                            const gboolean normalize_exposure,
                            extraction_result_t *result)
{
  const size_t width = roi_in->width;
  const size_t height = roi_in->height;
  const float radius_x = g->checker->radius * hypotf(1.f, g->checker->ratio) * g->safety_margin;
  const float radius_y = radius_x / g->checker->ratio;
 
  // The chart box is authored in preview-request pixels; this buffer may be a different grid.
  // Both radii stay in ideal chart units, so only the two homographies need the mapping.
  float homography[9];
  float inverse_homography[9];
  _map_homographies(g, box_map, homography, inverse_homography);
 
  dt_print(DT_DEBUG_DEV,
           "[channelmixerrgb] sampling %" G_GSIZE_FORMAT " patches over a %" G_GSIZE_FORMAT
           "x%" G_GSIZE_FORMAT " buffer, box scaled by (%.5f, %.5f) offset (%.1f, %.1f)\n",
           g->checker->patches, width, height, box_map->scale_x, box_map->scale_y,
           box_map->offset_x, box_map->offset_y);
 
  if(IS_NULL_PTR(g->delta_E_in))
  {
    g->delta_E_in = dt_alloc_align_float(g->checker->patches);
    if(IS_NULL_PTR(g->delta_E_in)) return 1;
  }
 
  /* Get the average color over each patch */
  for(size_t k = 0; k < g->checker->patches; k++)
  {
    // center of the patch in the ideal reference
    const point_t center = { g->checker->values[k].x, g->checker->values[k].y };
 
    // corners of the patch in the ideal reference
    const point_t corners[4] = { {center.x - radius_x, center.y - radius_y},
                                 {center.x + radius_x, center.y - radius_y},
                                 {center.x + radius_x, center.y + radius_y},
                                 {center.x - radius_x, center.y + radius_y} };
 
    // apply patch coordinates transform depending on perspective
    point_t new_corners[4];
    // find the bounding box of the patch at the same time
    size_t x_min = width - 1;
    size_t x_max = 0;
    size_t y_min = height - 1;
    size_t y_max = 0;
    for(size_t c = 0; c < 4; c++) {
      new_corners[c] = apply_homography(corners[c], homography);
      x_min = fminf(new_corners[c].x, x_min);
      x_max = fmaxf(new_corners[c].x, x_max);
      y_min = fminf(new_corners[c].y, y_min);
      y_max = fmaxf(new_corners[c].y, y_max);
    }
 
    x_min = CLAMP((size_t)floorf(x_min), 0, width - 1);
    x_max = CLAMP((size_t)ceilf(x_max), 0, width - 1);
    y_min = CLAMP((size_t)floorf(y_min), 0, height - 1);
    y_max = CLAMP((size_t)ceilf(y_max), 0, height - 1);
 
    // Get the average color on the patch
    patches[k * 4] = patches[k * 4 + 1] = patches[k * 4 + 2] = patches[k * 4 + 3] = 0.f;
    size_t num_elem = 0;
 
    // Loop through the rectangular bounding box
    for(size_t j = y_min; j < y_max; j++)
      for(size_t i = x_min; i < x_max; i++)
      {
        // Check if this pixel lies inside the sampling area and sample if it does
        point_t current_point = { i + 0.5f, j + 0.5f };
        current_point = apply_homography(current_point, inverse_homography);
        current_point.x -= center.x;
        current_point.y -= center.y;
 
        if(current_point.x < radius_x && current_point.x > -radius_x &&
           current_point.y < radius_y && current_point.y > -radius_y)
        {
          for(size_t c = 0; c < 3; c++)
          {
            patches[k * 4 + c] += in[(j * width + i) * 4 + c];
 
            // Debug : inpaint a black square in the preview to ensure the coordanites of
            // overlay drawings and actual pixel processing match
            // out[(j * width + i) * 4 + c] = 0.f;
          }
          num_elem++;
        }
      }
 
    if(num_elem == 0)
    {
      // Dividing by zero here hands the solver a NaN row, and it returns a matrix fitted on
      // nothing at all -- silently, with a plausible-looking delta E report next to it.
      dt_print(DT_DEBUG_ALWAYS,
               "[channelmixerrgb] patch %" G_GSIZE_FORMAT " (%s) sampled no pixel: the chart box"
               " does not lie on the %" G_GSIZE_FORMAT "x%" G_GSIZE_FORMAT " buffer."
               " Refusing to profile.\n",
               k, g->checker->values[k].name ? g->checker->values[k].name : "?", width, height);
      dt_control_log(_("color calibration: the chart area does not lie on the image"));
      return 1;
    }
 
    for(size_t c = 0; c < 3; c++) patches[k * 4 + c] /= (float)num_elem;
 
    // Convert to XYZ
    dt_aligned_pixel_t XYZ = { 0 };
    dot_product(patches + k * 4, RGB_to_XYZ, XYZ);
    for(size_t c = 0; c < 3; c++) patches[k * 4 + c] = XYZ[c];
  }
 
  // find reference white patch
  dt_aligned_pixel_t XYZ_white_ref;
  dt_Lab_to_XYZ(g->checker->values[g->checker->white].Lab, XYZ_white_ref);
  const float white_ref_norm = euclidean_norm(XYZ_white_ref);
 
  // find test white patch
  dt_aligned_pixel_t XYZ_white_test;
  for(size_t c = 0; c < 3; c++) XYZ_white_test[c] = patches[g->checker->white * 4 + c];
  const float white_test_norm = euclidean_norm(XYZ_white_test);
 
  /* match global exposure */
  // white exposure depends on camera settings and raw white point,
  // we want our profile to be independent from that
  float exposure = white_ref_norm / white_test_norm;
 
  /* Exposure compensation */
  // Ensure the relative luminance of the test patch (compared to white patch)
  // is the same as the relative luminance of the reference patch.
  // This compensate for lighting fall-off and unevenness
  if(normalize_exposure)
  {
    for(size_t k = 0; k < g->checker->patches; k++)
    {
      float *const sample = patches + k * 4;
 
      dt_aligned_pixel_t XYZ_ref;
      dt_Lab_to_XYZ(g->checker->values[k].Lab, XYZ_ref);
 
      const float sample_norm = euclidean_norm(sample);
      const float ref_norm = euclidean_norm(XYZ_ref);
 
      const float relative_luminance_test = sample_norm / white_test_norm;
      const float relative_luminance_ref = ref_norm / white_ref_norm;
 
      const float luma_correction = relative_luminance_ref / relative_luminance_test;
      for(size_t c = 0; c < 3; ++c) sample[c] *= luma_correction * exposure;
    }
  }
 
  // black point is evaluated by rawspeed on each picture using the dark pixels
  // we want our profile to be also independent from its discrepancies
  // so we convert back the patches to camera RGB space and search the best fit of
  // RGB_ref = exposure * (RGB_test - offset) for offset.
  float black = 0.f;
 
  if(XYZ_to_CAM)
  {
    float mean_ref = 0.f;
    float mean_test = 0.f;
 
    for(size_t k = 0; k < g->checker->patches; k++)
    {
      dt_aligned_pixel_t XYZ_ref, RGB_ref;
      dt_aligned_pixel_t XYZ_test, RGB_test;
 
      for(size_t c = 0; c < 3; c++) XYZ_test[c] = patches[k * 4 + c];
      dt_Lab_to_XYZ(g->checker->values[k].Lab, XYZ_ref);
 
      dot_product(XYZ_test, XYZ_to_CAM, RGB_test);
      dot_product(XYZ_ref, XYZ_to_CAM, RGB_ref);
 
      // From now on, we have all the reference and test data in camera RGB space
      // where exposure and black level are applied
 
      for(int c = 0; c < 3; c++)
      {
        mean_test += RGB_test[c];
        mean_ref += RGB_ref[c];
      }
    }
    mean_test /= 3.f * g->checker->patches;
    mean_ref /= 3.f * g->checker->patches;
 
    float variance = 0.f;
    float covariance = 0.f;
 
    for(size_t k = 0; k < g->checker->patches; k++)
    {
      dt_aligned_pixel_t XYZ_ref, RGB_ref;
      dt_aligned_pixel_t XYZ_test, RGB_test;
 
      for(size_t c = 0; c < 3; c++) XYZ_test[c] = patches[k * 4 + c];
      dt_Lab_to_XYZ(g->checker->values[k].Lab, XYZ_ref);
 
      dot_product(XYZ_test, XYZ_to_CAM, RGB_test);
      dot_product(XYZ_ref, XYZ_to_CAM, RGB_ref);
 
      for(int c = 0; c < 3; c++)
      {
        variance += sqf(RGB_test[c] - mean_test);
        // Both factors are centred on their OWN mean. Using mean_ref for the test term too is
        // algebraically the same covariance -- the surplus is (mean_test - mean_ref) times
        // sum(RGB_ref - mean_ref), and that sum is zero over the very set mean_ref averages --
        // but it computes it as a difference of two large numbers instead of a sum of small
        // ones, and it reads as a typo every time anyone audits this.
        covariance += (RGB_ref[c] - mean_ref) * (RGB_test[c] - mean_test);
      }
    }
    variance /= 3.f * g->checker->patches;
    covariance /= 3.f * g->checker->patches;
 
    // Here, we solve the least-squares problem RGB_ref = exposure * RGB_test + offset
    // using :
    //   exposure = covariance(RGB_test, RGB_ref) / variance(RGB_test)
    //   offset = mean(RGB_ref) - exposure * mean(RGB_test)
    exposure = covariance / variance;
    black = mean_ref - exposure * mean_test;
  }
 
  // the exposure module applies output  = (input - offset) * exposure
  // but we compute output = input * exposure + offset
  // so, rescale offset to adapt our offset to exposure module GUI
  black /= -exposure;
 
  result->black = black;
  result->exposure = exposure;
  return 0;
}
 
__DT_CLONE_TARGETS__
int extract_color_checker(const float *const restrict in, float *const restrict out,
                          const dt_iop_roi_t *const roi_in, dt_iop_channelmixer_rgb_gui_data_t *g,
                          const dt_iop_channelmixer_rgb_box_map_t *const box_map,
                          const dt_colormatrix_t RGB_to_XYZ, const dt_colormatrix_t XYZ_to_RGB,
                          const dt_colormatrix_t XYZ_to_CAM,
                          const dt_adaptation_t kind)
{
  float *const restrict patches = dt_alloc_align_float(g->checker->patches * 4);
  if(IS_NULL_PTR(patches)) return 1;
 
  dt_simd_memcpy(in, out, (size_t)roi_in->width * roi_in->height * 4);
 
  extraction_result_t extraction_result = { 0 };
  if(_extract_patches(out, roi_in, g, box_map, RGB_to_XYZ, XYZ_to_CAM, patches, TRUE, &extraction_result))
  {
    dt_free_align(patches);
    return 1;
  }
 
  // Compute the delta E
  float pre_wb_delta_E = 0.f;
  float pre_wb_max_delta_E = 0.f;
  compute_patches_delta_E(patches, g->checker, g->delta_E_in, &pre_wb_delta_E, &pre_wb_max_delta_E);
 
  /* find the scene illuminant */
 
  // find reference grey patch
  dt_aligned_pixel_t XYZ_grey_ref;
  dt_Lab_to_XYZ(g->checker->values[g->checker->middle_grey].Lab, XYZ_grey_ref);
 
  // find test grey patch
  dt_aligned_pixel_t XYZ_grey_test;
  for(size_t c = 0; c < 3; c++) XYZ_grey_test[c] = patches[g->checker->middle_grey * 4 + c];
 
  // compute reference illuminant
  dt_aligned_pixel_t D50_XYZ;
  illuminant_xy_to_XYZ(0.34567f, 0.35850f, D50_XYZ);
 
  // normalize luminances - note : illuminant is normalized by definition
  const float Y_test = XYZ_grey_test[1];
  const float Y_ref = XYZ_grey_ref[1];
  for(size_t c = 0; c < 3; c++)
  {
    XYZ_grey_ref[c] /= Y_ref;
    XYZ_grey_test[c] /= Y_test;
  }
 
  // convert XYZ to LMS
  dt_aligned_pixel_t LMS_grey_ref, LMS_grey_test, D50_LMS;
  dt_store_simd_aligned(LMS_grey_ref, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_grey_ref), kind));
  dt_store_simd_aligned(LMS_grey_test, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_grey_test), kind));
  dt_store_simd_aligned(D50_LMS, convert_any_XYZ_to_LMS(dt_load_simd_aligned(D50_XYZ), kind));
 
  // solve the equation to find the scene illuminant
  dt_aligned_pixel_t illuminant = { 0.0f };
  for(size_t c = 0; c < 3; c++) illuminant[c] = D50_LMS[c] * LMS_grey_test[c] / LMS_grey_ref[c];
 
  // convert back the illuminant to XYZ then xyY
  dt_aligned_pixel_t illuminant_XYZ, illuminant_xyY = { .0f };
  dt_store_simd_aligned(illuminant_XYZ, convert_any_LMS_to_XYZ(dt_load_simd_aligned(illuminant), kind));
  const float Y_illu = illuminant_XYZ[1];
  for(size_t c = 0; c < 3; c++) illuminant_XYZ[c] /= Y_illu;
  dt_XYZ_to_xyY(illuminant_XYZ, illuminant_xyY);
 
  // save the illuminant in GUI struct for commit
  g->xy[0] = illuminant_xyY[0];
  g->xy[1] = illuminant_xyY[1];
 
  // and recompute back the LMS to be sure we use the parameters that will be computed later
  illuminant_xy_to_XYZ(illuminant_xyY[0], illuminant_xyY[1], illuminant_XYZ);
  dt_store_simd_aligned(illuminant, convert_any_XYZ_to_LMS(dt_load_simd_aligned(illuminant_XYZ), kind));
  const float p = powf(0.818155f / illuminant[2], 0.0834f);
 
  /* White-balance the patches */
  for(size_t k = 0; k < g->checker->patches; k++)
  {
    // keep in synch with loop_switch() from process()
    float *const sample = patches + k * 4;
    const float Y = sample[1];
    downscale_vector(sample, Y);
 
    dt_aligned_pixel_t LMS;
    dt_store_simd_aligned(LMS, convert_any_XYZ_to_LMS(dt_load_simd_aligned(sample), kind));
 
    dt_aligned_pixel_t temp;
    const dt_aligned_pixel_simd_t LMS_v = dt_load_simd_aligned(LMS);
    const dt_aligned_pixel_simd_t illuminant_v = dt_load_simd_aligned(illuminant);
 
    switch(kind)
    {
      case DT_ADAPTATION_FULL_BRADFORD:
      {
        dt_store_simd_aligned(temp, bradford_adapt_D50(LMS_v, illuminant_v, p, TRUE));
        break;
      }
      case DT_ADAPTATION_LINEAR_BRADFORD:
      {
        dt_store_simd_aligned(temp, bradford_adapt_D50(LMS_v, illuminant_v, 1.f, FALSE));
        break;
      }
      case DT_ADAPTATION_CAT16:
      {
        dt_store_simd_aligned(temp, CAT16_adapt_D50(LMS_v, illuminant_v, 1.f, TRUE)); // force full-adaptation
        break;
      }
      case DT_ADAPTATION_XYZ:
      {
        dt_store_simd_aligned(temp, XYZ_adapt_D50(LMS_v, illuminant_v));
        break;
      }
      case DT_ADAPTATION_RGB:
      case DT_ADAPTATION_LAST:
      default:
      {
        // No white balance.
        for(size_t c = 0; c < 3; ++c) temp[c] = LMS[c];
        break;
      }
    }
 
    dt_store_simd_aligned(sample, convert_any_LMS_to_XYZ(dt_load_simd_aligned(temp), kind));
    upscale_vector(sample, Y);
  }
 
  // Compute the delta E
  float post_wb_delta_E = 0.f;
  float post_wb_max_delta_E = 0.f;
  compute_patches_delta_E(patches, g->checker, g->delta_E_in, &post_wb_delta_E, &post_wb_max_delta_E);
 
  /* Compute the matrix of mix */
  double *const restrict Y = dt_alloc_align(g->checker->patches * 3 * sizeof(double));
  double *const restrict A = dt_alloc_align(g->checker->patches * 3 * 9 * sizeof(double));
  if(IS_NULL_PTR(Y) || IS_NULL_PTR(A))
  {
    dt_free_align(Y);
    dt_free_align(A);
    dt_free_align(patches);
    return 1;
  }
 
  for(size_t k = 0; k < g->checker->patches; k++)
  {
    float *const sample = patches + k * 4;
    dt_aligned_pixel_t LMS_test;
    dt_store_simd_aligned(LMS_test, convert_any_XYZ_to_LMS(dt_load_simd_aligned(sample), kind));
 
    const float *const reference = g->checker->values[k].Lab;
    dt_aligned_pixel_t XYZ_ref, LMS_ref;
    dt_Lab_to_XYZ(reference, XYZ_ref);
    dt_store_simd_aligned(LMS_ref, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_ref), kind));
 
    // get the optimization weights
    float w = 1.f;
    if(g->optimization == DT_SOLVE_OPTIMIZE_NONE)
      w = sqrtf(1.f / (float)g->checker->patches);
    else if(g->optimization == DT_SOLVE_OPTIMIZE_HIGH_SAT)
      w = sqrtf(hypotf(reference[1] / 128.f, reference[2] / 128.f));
    else if(g->optimization == DT_SOLVE_OPTIMIZE_LOW_SAT)
      w = sqrtf(1.f - hypotf(reference[1] / 128.f, reference[2] / 128.f));
    else if(g->optimization == DT_SOLVE_OPTIMIZE_SKIN)
    {
      // average skin hue angle is 1.0 rad, hue range is [0.75 ; 1.25]
      const float ref_hue = 1.f;
      GET_WEIGHT;
    }
    else if(g->optimization == DT_SOLVE_OPTIMIZE_FOLIAGE)
    {
      // average foliage hue angle is 2.23 rad, hue range is [1.94 ; 2.44]
      const float ref_hue = 2.23f;
      GET_WEIGHT;
    }
    else if(g->optimization == DT_SOLVE_OPTIMIZE_SKY)
    {
      // average sky/water hue angle is -1.93 rad, hue range is [-1.64 ; -2.41]
      const float ref_hue = -1.93f;
      GET_WEIGHT;
    }
    else if(g->optimization == DT_SOLVE_OPTIMIZE_AVG_DELTA_E)
      w = sqrtf(sqrtf(1.f / g->delta_E_in[k]));
    else if(g->optimization == DT_SOLVE_OPTIMIZE_MAX_DELTA_E)
      w = sqrtf(sqrtf(g->delta_E_in[k]));
 
    // fill 3 rows of the y column vector
    for(size_t c = 0; c < 3; c++) Y[k * 3 + c] = w * LMS_ref[c];
 
    // fill line one of the A matrix
    A[k * 3 * 9 + 0] = w * LMS_test[0];
    A[k * 3 * 9 + 1] = w * LMS_test[1];
    A[k * 3 * 9 + 2] = w * LMS_test[2];
    A[k * 3 * 9 + 3] = 0.f;
    A[k * 3 * 9 + 4] = 0.f;
    A[k * 3 * 9 + 5] = 0.f;
    A[k * 3 * 9 + 6] = 0.f;
    A[k * 3 * 9 + 7] = 0.f;
    A[k * 3 * 9 + 8] = 0.f;
 
    // fill line two of the A matrix
    A[k * 3 * 9 + 9 + 0] = 0.f;
    A[k * 3 * 9 + 9 + 1] = 0.f;
    A[k * 3 * 9 + 9 + 2] = 0.f;
    A[k * 3 * 9 + 9 + 3] = w * LMS_test[0];
    A[k * 3 * 9 + 9 + 4] = w * LMS_test[1];
    A[k * 3 * 9 + 9 + 5] = w * LMS_test[2];
    A[k * 3 * 9 + 9 + 6] = 0.f;
    A[k * 3 * 9 + 9 + 7] = 0.f;
    A[k * 3 * 9 + 9 + 8] = 0.f;
 
    // fill line three of the A matrix
    A[k * 3 * 9 + 18 + 0] = 0.f;
    A[k * 3 * 9 + 18 + 1] = 0.f;
    A[k * 3 * 9 + 18 + 2] = 0.f;
    A[k * 3 * 9 + 18 + 3] = 0.f;
    A[k * 3 * 9 + 18 + 4] = 0.f;
    A[k * 3 * 9 + 18 + 5] = 0.f;
    A[k * 3 * 9 + 18 + 6] = w * LMS_test[0];
    A[k * 3 * 9 + 18 + 7] = w * LMS_test[1];
    A[k * 3 * 9 + 18 + 8] = w * LMS_test[2];
  }
 
  if(pseudo_solve_gaussian(A, Y, g->checker->patches * 3, 9, TRUE) != 0)
  {
    dt_free_align(Y);
    dt_free_align(A);
    dt_free_align(patches);
    return 1;
  }
 
  // repack the matrix
  repack_double3x3_to_3xSSE(Y, g->mix);
 
  dt_free_align(Y);
  dt_free_align(A);
 
  // apply the matrix mix
  for(size_t k = 0; k < g->checker->patches; k++)
  {
    float *const sample = patches + k * 4;
    dt_aligned_pixel_t LMS_test;
    dt_aligned_pixel_t temp = { 0.f };
 
    // Restore the original exposure of the patch
    for(size_t c = 0; c < 3; c++) temp[c] = sample[c];
 
    dt_store_simd_aligned(LMS_test, convert_any_XYZ_to_LMS(dt_load_simd_aligned(temp), kind));
      dot_product(LMS_test, g->mix, temp);
    dt_store_simd_aligned(sample, convert_any_LMS_to_XYZ(dt_load_simd_aligned(temp), kind));
  }
 
  // Compute the delta E
  float post_mix_delta_E = 0.f;
  float post_mix_max_delta_E = 0.f;
  compute_patches_delta_E(patches, g->checker, g->delta_E_in, &post_mix_delta_E, &post_mix_max_delta_E);
 
  // get the temperature
  float temperature;
  dt_illuminant_t test_illuminant;
  float x = illuminant_xyY[0];
  float y = illuminant_xyY[1];
  check_if_close_to_daylight(x, y, &temperature, &test_illuminant, NULL);
  gchar *string;
  if(test_illuminant == DT_ILLUMINANT_D)
    string = _("(daylight)");
  else if(test_illuminant == DT_ILLUMINANT_BB)
    string = _("(black body)");
  else
    string = _("(invalid)");
 
  gchar *diagnostic;
  if(post_mix_delta_E <= 1.2f)
    diagnostic = _("very good");
  else if(post_mix_delta_E <= 2.3f)
    diagnostic = _("good");
  else if(post_mix_delta_E <= 3.4f)
    diagnostic = _("passable");
  else
    diagnostic = _("bad");
 
  g->profile_ready = TRUE;
 
  // Update GUI label
  dt_free(g->delta_E_label_text);
  g->delta_E_label_text
      = g_strdup_printf(_("\n<b>Profile quality report: %s</b>\n"
                          "input \316\224E: \tavg. %.2f ; \tmax. %.2f\n"
                          "WB \316\224E: \tavg. %.2f; \tmax. %.2f\n"
                          "output \316\224E: \tavg. %.2f; \tmax. %.2f\n\n"
                          "<b>Profile data</b>\n"
                          "illuminant:  \t%.0f K \t%s\n"
                          "matrix in adaptation space:\n"
                          "<tt>%+.4f \t%+.4f \t%+.4f\n"
                          "%+.4f \t%+.4f \t%+.4f\n"
                          "%+.4f \t%+.4f \t%+.4f</tt>\n\n"
                          "<b>Normalization values</b>\n"
                          "exposure compensation: \t%+.2f EV\n"
                          "black offset: \t%+.4f"
                          ),
                        diagnostic, pre_wb_delta_E, pre_wb_max_delta_E, post_wb_delta_E, post_wb_max_delta_E,
                        post_mix_delta_E, post_mix_max_delta_E, temperature, string, g->mix[0][0], g->mix[0][1],
                        g->mix[0][2], g->mix[1][0], g->mix[1][1], g->mix[1][2], g->mix[2][0], g->mix[2][1],
                        g->mix[2][2], log2f(extraction_result.exposure), extraction_result.black);
 
  dt_free_align(patches);
  return 0;
}
 
int validate_color_checker(const float *const restrict in,
                           const dt_iop_roi_t *const roi_in, dt_iop_channelmixer_rgb_gui_data_t *g,
                           const dt_iop_channelmixer_rgb_box_map_t *const box_map,
                           const dt_colormatrix_t RGB_to_XYZ, const dt_colormatrix_t XYZ_to_RGB, const dt_colormatrix_t XYZ_to_CAM)
{
  float *const restrict patches = dt_alloc_align_float(4 * g->checker->patches);
  if(IS_NULL_PTR(patches)) return 1;
  extraction_result_t extraction_result = { 0 };
  if(_extract_patches(in, roi_in, g, box_map, RGB_to_XYZ, XYZ_to_CAM, patches, FALSE, &extraction_result))
  {
    dt_free_align(patches);
    return 1;
  }
 
  // Compute the delta E
  float pre_wb_delta_E = 0.f;
  float pre_wb_max_delta_E = 0.f;
  compute_patches_delta_E(patches, g->checker, g->delta_E_in, &pre_wb_delta_E, &pre_wb_max_delta_E);
 
  gchar *diagnostic;
  if(pre_wb_delta_E <= 1.2f)
    diagnostic = _("very good");
  else if(pre_wb_delta_E <= 2.3f)
    diagnostic = _("good");
  else if(pre_wb_delta_E <= 3.4f)
    diagnostic = _("passable");
  else
    diagnostic = _("bad");
 
  // Update GUI label
  dt_free(g->delta_E_label_text);
  g->delta_E_label_text = g_strdup_printf(_("\n<b>Profile quality report: %s</b>\n"
                                            "output \316\224E: \tavg. %.2f; \tmax. %.2f\n\n"
                                            "<b>Normalization values</b>\n"
                                            "exposure compensation: \t%+.2f EV\n"
                                            "black offset: \t%+.4f"),
                                          diagnostic, pre_wb_delta_E, pre_wb_max_delta_E, log2f(extraction_result.exposure),
                                          extraction_result.black);
 
  dt_free_align(patches);
  return 0;
}
 
int process(struct dt_iop_module_t *self, const dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece,
             const void *const restrict ivoid, void *const restrict ovoid)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  const dt_iop_roi_t *const roi_out = &piece->roi_out;
  dt_iop_channelmixer_rbg_data_t *data = (dt_iop_channelmixer_rbg_data_t *)piece->data;
  const struct dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_current_profile_info(self, pipe);
  const struct dt_iop_order_iccprofile_info_t *const input_profile = dt_ioppr_get_pipe_input_profile_info(pipe);
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  declare_cat_on_pipe(self, FALSE);
 
  dt_colormatrix_t RGB_to_XYZ;
  dt_colormatrix_t XYZ_to_RGB;
  dt_colormatrix_t XYZ_to_CAM;
 
  // repack the matrices as flat AVX2-compliant matrice
  if(!IS_NULL_PTR(work_profile))
  {
    // work profile can't be fetched in commit_params since it is not yet initialised
    memcpy(RGB_to_XYZ, work_profile->matrix_in, sizeof(RGB_to_XYZ));
    memcpy(XYZ_to_RGB, work_profile->matrix_out, sizeof(XYZ_to_RGB));
    memcpy(XYZ_to_CAM, input_profile->matrix_out, sizeof(XYZ_to_CAM));
  }
 
  const size_t ch = 4;
 
  const float *const restrict in = (const float *const restrict)ivoid;
  float *const restrict out = (float *const restrict)ovoid;
 
  // auto-detect WB upon request
  if(self->dev->gui_attached && g)
  {
    gboolean exit = FALSE;
 
    if(g->run_profile && pipe->type == DT_DEV_PIXELPIPE_PREVIEW)
    {
      dt_iop_gui_enter_critical_section(self);
      const dt_iop_channelmixer_rgb_box_map_t box_map = _box_map(pipe, roi_in);
      const int err = extract_color_checker(in, out, roi_in, g, &box_map,
                                            RGB_to_XYZ, XYZ_to_RGB, XYZ_to_CAM, data->adaptation);
      g->run_profile = FALSE;
      dt_iop_set_cache_bypass(self, FALSE);
      dt_iop_gui_leave_critical_section(self);
      if(err) return 1;
    }
 
    if(data->illuminant_type == DT_ILLUMINANT_DETECT_EDGES || data->illuminant_type == DT_ILLUMINANT_DETECT_SURFACES)
    {
      if(pipe->type == DT_DEV_PIXELPIPE_FULL)
      {
        // detection on full image only
        dt_iop_gui_enter_critical_section(self);
        const int err = auto_detect_WB(in, data->illuminant_type, roi_in->width, roi_in->height, ch, RGB_to_XYZ, g->XYZ);
        dt_iop_gui_leave_critical_section(self);
        if(err) return 1;
      }
 
      // passthrough pixels
      dt_iop_image_copy_by_size(out, in, roi_in->width, roi_in->height, ch);
 
      dt_control_log(_("auto-detection of white balance completed"));
 
      exit = TRUE;
    }
 
    if(exit) return 0;
  }
 
  if(data->illuminant_type == DT_ILLUMINANT_CAMERA)
  {
    // The camera illuminant is a behaviour rather than a preset of values:
    // it uses whatever is in the RAW EXIF. But it depends on what temperature.c is doing
    // and needs to be updated accordingly, to give a consistent result.
    // We initialise the CAT defaults using the temperature coeffs at startup, but if temperature
    // is changed later, we get no notification of the change here, so we can't update the defaults.
    // So we need to re-run the detection at runtime...
    float x, y;
    dt_aligned_pixel_t custom_wb;
    // Pipeline thread: source temperature's WB from the per-piece descriptor propagated in pipe
    // order (temperature writes piece->dsc_out.temperature.coeffs), NOT from dev->proxy.
    _custom_wb_from_coeffs(self, piece->dsc_in.temperature.coeffs, custom_wb);
 
    if(find_temperature_from_raw_coeffs(&(self->dev->image_storage), custom_wb, &(x), &(y)))
    {
      // Convert illuminant from xyY to XYZ
      dt_aligned_pixel_t XYZ;
      illuminant_xy_to_XYZ(x, y, XYZ);
 
      // Convert illuminant from XYZ to Bradford modified LMS
      dt_store_simd_aligned(data->illuminant, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ), data->adaptation));
      data->illuminant[3] = 0.f;
    }
    else
    {
      // just use whatever was defined in commit_params hoping the defaults work...
    }
  }
 
  // force loop unswitching in a controlled way
  switch(data->adaptation)
  {
    case DT_ADAPTATION_FULL_BRADFORD:
    {
      loop_switch(in, out, roi_out->width, roi_out->height, ch,
                  XYZ_to_RGB, RGB_to_XYZ, data->MIX,
                  data->illuminant, data->saturation, data->lightness, data->grey,
                  data->p, data->gamut, data->clip, data->apply_grey, DT_ADAPTATION_FULL_BRADFORD, data->version);
      break;
    }
    case DT_ADAPTATION_LINEAR_BRADFORD:
    {
      loop_switch(in, out, roi_out->width, roi_out->height, ch,
                  XYZ_to_RGB, RGB_to_XYZ, data->MIX,
                  data->illuminant, data->saturation, data->lightness, data->grey,
                  data->p, data->gamut, data->clip, data->apply_grey, DT_ADAPTATION_LINEAR_BRADFORD, data->version);
      break;
    }
    case DT_ADAPTATION_CAT16:
    {
      loop_switch(in, out, roi_out->width, roi_out->height, ch,
                  XYZ_to_RGB, RGB_to_XYZ, data->MIX,
                  data->illuminant, data->saturation, data->lightness, data->grey,
                  data->p, data->gamut, data->clip, data->apply_grey, DT_ADAPTATION_CAT16, data->version);
      break;
    }
    case DT_ADAPTATION_XYZ:
    {
      loop_switch(in, out, roi_out->width, roi_out->height, ch,
                  XYZ_to_RGB, RGB_to_XYZ, data->MIX,
                  data->illuminant, data->saturation, data->lightness, data->grey,
                  data->p, data->gamut, data->clip, data->apply_grey, DT_ADAPTATION_XYZ, data->version);
      break;
    }
    case DT_ADAPTATION_RGB:
    {
      loop_switch(in, out, roi_out->width, roi_out->height, ch,
                  XYZ_to_RGB, RGB_to_XYZ, data->MIX,
                  data->illuminant, data->saturation, data->lightness, data->grey,
                  data->p, data->gamut, data->clip, data->apply_grey, DT_ADAPTATION_RGB, data->version);
      break;
    }
    case DT_ADAPTATION_LAST:
    default:
    {
      break;
    }
  }
 
  // run dE validation at output
  if(self->dev->gui_attached && g)
    if(g->run_validation && pipe->type == DT_DEV_PIXELPIPE_PREVIEW)
    {
      const dt_iop_channelmixer_rgb_box_map_t box_map = _box_map(pipe, roi_out);
      const int err = validate_color_checker(out, roi_out, g, &box_map, RGB_to_XYZ, XYZ_to_RGB, XYZ_to_CAM);
      g->run_validation = FALSE;
      if(err) return 1;
    }
 
  return 0;
}
 
#if HAVE_OPENCL
int process_cl(struct dt_iop_module_t *self, const dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece, cl_mem dev_in, cl_mem dev_out)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  dt_iop_channelmixer_rbg_data_t *const d = (dt_iop_channelmixer_rbg_data_t *)piece->data;
  dt_iop_channelmixer_rgb_global_data_t *const gd = (dt_iop_channelmixer_rgb_global_data_t *)self->global_data;
  const struct dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_current_profile_info(self, pipe);
  //dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)self->gui_data;
 
  declare_cat_on_pipe(self, FALSE);
 
  if(d->illuminant_type == DT_ILLUMINANT_CAMERA)
  {
    // The camera illuminant is a behaviour rather than a preset of values:
    // it uses whatever is in the RAW EXIF. But it depends on what temperature.c is doing
    // and needs to be updated accordingly, to give a consistent result.
    // We initialise the CAT defaults using the temperature coeffs at startup, but if temperature
    // is changed later, we get no notification of the change here, so we can't update the defaults.
    // So we need to re-run the detection at runtime...
    float x, y;
    dt_aligned_pixel_t custom_wb;
    // Pipeline thread: source temperature's WB from the per-piece descriptor propagated in pipe
    // order (temperature writes piece->dsc_out.temperature.coeffs), NOT from dev->proxy.
    _custom_wb_from_coeffs(self, piece->dsc_in.temperature.coeffs, custom_wb);
 
    if(find_temperature_from_raw_coeffs(&(self->dev->image_storage), custom_wb, &(x), &(y)))
    {
      // Convert illuminant from xyY to XYZ
      dt_aligned_pixel_t XYZ;
      illuminant_xy_to_XYZ(x, y, XYZ);
 
      // Convert illuminant from XYZ to Bradford modified LMS
      dt_store_simd_aligned(d->illuminant, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ), d->adaptation));
      d->illuminant[3] = 0.f;
    }
  }
 
  cl_int err = -999;
 
  const int devid = pipe->devid;
  const int width = roi_in->width;
  const int height = roi_in->height;
 
  size_t sizes[] = { ROUNDUPDWD(width, devid), ROUNDUPDHT(height, devid), 1 };
 
  cl_mem input_matrix_cl = NULL;
  cl_mem output_matrix_cl = NULL;
 
  float input_matrix_3x4[12];
  float output_matrix_3x4[12];
  float mix_matrix_3x4[12];
  pack_3xSSE_to_3x4(work_profile->matrix_in, input_matrix_3x4);
  pack_3xSSE_to_3x4(work_profile->matrix_out, output_matrix_3x4);
  pack_3xSSE_to_3x4(d->MIX, mix_matrix_3x4);
 
  input_matrix_cl = dt_opencl_copy_host_to_device_constant(devid, sizeof(input_matrix_3x4), input_matrix_3x4);
  output_matrix_cl = dt_opencl_copy_host_to_device_constant(devid, sizeof(output_matrix_3x4), output_matrix_3x4);
  cl_mem MIX_cl = dt_opencl_copy_host_to_device_constant(devid, sizeof(mix_matrix_3x4), mix_matrix_3x4);
 
  // select the right kernel for the current LMS space
  int kernel = gd->kernel_channelmixer_rgb_rgb;
 
  switch(d->adaptation)
  {
    case DT_ADAPTATION_FULL_BRADFORD:
    {
      kernel = gd->kernel_channelmixer_rgb_bradford_full;
      break;
    }
    case DT_ADAPTATION_LINEAR_BRADFORD:
    {
      kernel = gd->kernel_channelmixer_rgb_bradford_linear;
      break;
    }
    case DT_ADAPTATION_CAT16:
    {
      kernel = gd->kernel_channelmixer_rgb_cat16;
      break;
    }
    case DT_ADAPTATION_XYZ:
    {
      kernel = gd->kernel_channelmixer_rgb_xyz;
      break;
     }
    case DT_ADAPTATION_RGB:
    case DT_ADAPTATION_LAST:
    default:
    {
      kernel = gd->kernel_channelmixer_rgb_rgb;
      break;
    }
  }
 
  dt_opencl_set_kernel_arg(devid, kernel, 0, sizeof(cl_mem), (void *)&dev_in);
  dt_opencl_set_kernel_arg(devid, kernel, 1, sizeof(cl_mem), (void *)&dev_out);
  dt_opencl_set_kernel_arg(devid, kernel, 2, sizeof(int), (void *)&width);
  dt_opencl_set_kernel_arg(devid, kernel, 3, sizeof(int), (void *)&height);
  dt_opencl_set_kernel_arg(devid, kernel, 4, sizeof(cl_mem), (void *)&input_matrix_cl);
  dt_opencl_set_kernel_arg(devid, kernel, 5, sizeof(cl_mem), (void *)&output_matrix_cl);
  dt_opencl_set_kernel_arg(devid, kernel, 6, sizeof(cl_mem), (void *)&MIX_cl);
  dt_opencl_set_kernel_arg(devid, kernel, 7, 4 * sizeof(float), (void *)&d->illuminant);
  dt_opencl_set_kernel_arg(devid, kernel, 8, 4 * sizeof(float), (void *)&d->saturation);
  dt_opencl_set_kernel_arg(devid, kernel, 9, 4 * sizeof(float), (void *)&d->lightness);
  dt_opencl_set_kernel_arg(devid, kernel, 10, 4 * sizeof(float), (void *)&d->grey);
  dt_opencl_set_kernel_arg(devid, kernel, 11, sizeof(float), (void *)&d->p);
  dt_opencl_set_kernel_arg(devid, kernel, 12, sizeof(float), (void *)&d->gamut);
  dt_opencl_set_kernel_arg(devid, kernel, 13, sizeof(int), (void *)&d->clip);
  dt_opencl_set_kernel_arg(devid, kernel, 14, sizeof(int), (void *)&d->apply_grey);
  dt_opencl_set_kernel_arg(devid, kernel, 15, sizeof(int), (void *)&d->version);
  err = dt_opencl_enqueue_kernel_2d(devid, kernel, sizes);
  if(err != CL_SUCCESS) goto error;
 
  dt_opencl_release_mem_object(input_matrix_cl);
  dt_opencl_release_mem_object(output_matrix_cl);
  dt_opencl_release_mem_object(MIX_cl);
  return TRUE;
 
error:
  dt_opencl_release_mem_object(input_matrix_cl);
  dt_opencl_release_mem_object(output_matrix_cl);
  dt_opencl_release_mem_object(MIX_cl);
  dt_print(DT_DEBUG_OPENCL, "[opencl_channelmixerrgb] couldn't enqueue kernel! %d\n", err);
  return FALSE;
}
 
void init_global(dt_iop_module_so_t *module)
{
  const int program = 32; // extended.cl in programs.conf
  dt_iop_channelmixer_rgb_global_data_t *gd
      = (dt_iop_channelmixer_rgb_global_data_t *)malloc(sizeof(dt_iop_channelmixer_rgb_global_data_t));
 
  module->data = gd;
  gd->kernel_channelmixer_rgb_cat16 = dt_opencl_create_kernel(program, "channelmixerrgb_CAT16");
  gd->kernel_channelmixer_rgb_bradford_full = dt_opencl_create_kernel(program, "channelmixerrgb_bradford_full");
  gd->kernel_channelmixer_rgb_bradford_linear = dt_opencl_create_kernel(program, "channelmixerrgb_bradford_linear");
  gd->kernel_channelmixer_rgb_xyz = dt_opencl_create_kernel(program, "channelmixerrgb_XYZ");
  gd->kernel_channelmixer_rgb_rgb = dt_opencl_create_kernel(program, "channelmixerrgb_RGB");
}
 
 
void cleanup_global(dt_iop_module_so_t *module)
{
  dt_iop_channelmixer_rgb_global_data_t *gd = (dt_iop_channelmixer_rgb_global_data_t *)module->data;
  dt_opencl_free_kernel(gd->kernel_channelmixer_rgb_cat16);
  dt_opencl_free_kernel(gd->kernel_channelmixer_rgb_bradford_full);
  dt_opencl_free_kernel(gd->kernel_channelmixer_rgb_bradford_linear);
  dt_opencl_free_kernel(gd->kernel_channelmixer_rgb_xyz);
  dt_opencl_free_kernel(gd->kernel_channelmixer_rgb_rgb);
  dt_free(module->data);
}
#endif
 
 
static inline void update_bounding_box(dt_iop_channelmixer_rgb_gui_data_t *g,
                                       const float x_increment, const float y_increment)
{
  // update box nodes
  for(size_t k = 0; k < 4; k++)
  {
    if(g->active_node[k])
    {
      g->box[k].x += x_increment;
      g->box[k].y += y_increment;
    }
  }
 
  // update the homography
  get_homography(g->ideal_box, g->box, g->homography);
  get_homography(g->box, g->ideal_box, g->inverse_homography);
}
 
static inline void init_bounding_box(dt_iop_channelmixer_rgb_gui_data_t *g, const float width, const float height)
{
  if(g->checker && !g->checker_ready)
  {
    // top left
    g->box[0].x = g->box[0].y = 10.;
 
    // top right
    g->box[1].x = (width - 10.);
    g->box[1].y = g->box[0].y;
 
    // bottom right
    g->box[2].x = g->box[1].x;
    g->box[2].y = (width - 10.) * g->checker->ratio;
 
    // bottom left
    g->box[3].x = g->box[0].x;
    g->box[3].y = g->box[2].y;
 
    g->checker_ready = TRUE;
  }
 
  g->center_box.x = 0.5f;
  g->center_box.y = 0.5f;
 
  g->ideal_box[0].x = 0.f;
  g->ideal_box[0].y = 0.f;
  g->ideal_box[1].x = 1.f;
  g->ideal_box[1].y = 0.f;
  g->ideal_box[2].x = 1.f;
  g->ideal_box[2].y = 1.f;
  g->ideal_box[3].x = 0.f;
  g->ideal_box[3].y = 1.f;
 
  update_bounding_box(g, 0.f, 0.f);
}
 
 
 
int mouse_moved(struct dt_iop_module_t *self, double x, double y, double pressure, int which)
{
  if(!self->enabled) return 0;
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g) || !g->is_profiling_started) return 0;
  if(g->box[0].x == -1.0f || g->box[1].y == -1.0f) return 0;
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return 0;
 
  float pzxpy[2] = { (float)x, (float)y };
  dt_dev_coordinates_widget_to_image_norm(dev, pzxpy, 1);
  dt_dev_coordinates_image_norm_to_preview_abs(dev, pzxpy, 1);
  const float pzx = pzxpy[0];
  const float pzy = pzxpy[1];
 
  // if dragging and dropping, don't update active nodes,
  // just update cursor coordinates then redraw
  // this ensure smooth updates
  if(g->drag_drop)
  {
    dt_iop_gui_enter_critical_section(self);
    g->click_end.x = pzx;
    g->click_end.y = pzy;
 
    update_bounding_box(g, g->click_end.x - g->click_start.x, g->click_end.y - g->click_start.y);
 
    g->click_start.x = pzx;
    g->click_start.y = pzy;
    dt_iop_gui_leave_critical_section(self);
 
    dt_control_queue_redraw_center();
    return 1;
  }
 
  // Find out if we are close to a node
  dt_iop_gui_enter_critical_section(self);
  g->is_cursor_close = FALSE;
 
  for(size_t k = 0; k < 4; k++)
  {
    if(hypotf(pzx - g->box[k].x, pzy - g->box[k].y) < 15.f)
    {
      g->active_node[k] = TRUE;
      g->is_cursor_close = TRUE;
    }
    else
      g->active_node[k] = FALSE;
  }
  dt_iop_gui_leave_critical_section(self);
 
  // if cursor is close from a node, remove the system pointer arrow to prevent hiding the spot behind it
  if(g->is_cursor_close)
  {
    dt_control_set_cursor_visible(FALSE);
  }
  else
  {
    // Un-hide the cursor (it may have been hidden by the branch above) and leave it at
    // darkroom's own default (dot/crosshair/left_ptr, already queued per position by
    // _darkroom_set_default_cursor before this handler runs) instead of forcing "default".
    dt_control_set_cursor_visible(TRUE);
  }
 
  dt_control_queue_redraw_center();
 
  return 1;
}
 
int button_pressed(struct dt_iop_module_t *self, double x, double y, double pressure, int which, int type,
                   uint32_t state)
{
  if(!self->enabled) return 0;
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g) || !g->is_profiling_started) return 0;
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return 0;
 
  // double click : reset the perspective correction
  if(type == GDK_DOUBLE_BUTTON_PRESS)
  {
    dt_iop_gui_enter_critical_section(self);
    g->checker_ready = FALSE;
    g->profile_ready = FALSE;
    init_bounding_box(g, wd, ht);
    dt_iop_gui_leave_critical_section(self);
 
    dt_control_queue_redraw_center();
    return 1;
  }
 
  // bounded box not inited, abort
  if(g->box[0].x == -1.0f || g->box[1].y == -1.0f) return 0;
 
  // cursor is not on a node, abort
  if(!g->is_cursor_close) return 0;
 
  float pzxpy[2] = { (float)x, (float)y };
  dt_dev_coordinates_widget_to_image_norm(dev, pzxpy, 1);
  dt_dev_coordinates_image_norm_to_preview_abs(dev, pzxpy, 1);
  const float pzx = pzxpy[0];
  const float pzy = pzxpy[1];
 
  dt_iop_gui_enter_critical_section(self);
  g->drag_drop = TRUE;
  g->click_start.x = pzx;
  g->click_start.y = pzy;
  dt_iop_gui_leave_critical_section(self);
 
  dt_control_queue_redraw_center();
 
  return 1;
}
 
int button_released(struct dt_iop_module_t *self, double x, double y, int which, uint32_t state)
{
  if(!self->enabled) return 0;
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g) || !g->is_profiling_started) return 0;
  if(g->box[0].x == -1.0f || g->box[1].y == -1.0f) return 0;
  if(!g->is_cursor_close || !g->drag_drop) return 0;
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return 0;
 
  float pzxpy[2] = { (float)x, (float)y };
  dt_dev_coordinates_widget_to_image_norm(dev, pzxpy, 1);
  dt_dev_coordinates_image_norm_to_preview_abs(dev, pzxpy, 1);
  const float pzx = pzxpy[0];
  const float pzy = pzxpy[1];
 
  dt_iop_gui_enter_critical_section(self);
  g->drag_drop = FALSE;
  g->click_end.x = pzx;
  g->click_end.y = pzy;
  update_bounding_box(g, g->click_end.x - g->click_start.x, g->click_end.y - g->click_start.y);
  dt_iop_gui_leave_critical_section(self);
 
  dt_control_queue_redraw_center();
 
  return 1;
}
 
void gui_post_expose(struct dt_iop_module_t *self, cairo_t *cr, int32_t width, int32_t height,
                     int32_t pointerx, int32_t pointery)
{
  const dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
  if(IS_NULL_PTR(work_profile)) return;
 
  const dt_iop_channelmixer_rgb_gui_data_t *g = (const dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g) || !g->is_profiling_started) return;
 
  // Rescale and shift Cairo drawing coordinates
  dt_develop_t *dev = self->dev;
  if(dt_dev_rescale_roi(dev, cr, width, height)) return;
  const float zoom_scale = dt_dev_get_overlay_scale(dev);
 
  cairo_set_line_width(cr, 2.0 / zoom_scale);
  const double origin = 9. / zoom_scale;
  const double destination = 18. / zoom_scale;
 
  for(size_t k = 0; k < 4; k++)
  {
    if(g->active_node[k])
    {
      // draw cross hair
      cairo_set_source_rgba(cr, 1., 1., 1., 1.);
 
      cairo_move_to(cr, g->box[k].x - origin, g->box[k].y);
      cairo_line_to(cr, g->box[k].x - destination, g->box[k].y);
 
      cairo_move_to(cr, g->box[k].x + origin, g->box[k].y);
      cairo_line_to(cr, g->box[k].x + destination, g->box[k].y);
 
      cairo_move_to(cr, g->box[k].x, g->box[k].y - origin);
      cairo_line_to(cr, g->box[k].x, g->box[k].y - destination);
 
      cairo_move_to(cr, g->box[k].x, g->box[k].y + origin);
      cairo_line_to(cr, g->box[k].x, g->box[k].y + destination);
 
      cairo_stroke(cr);
    }
 
    // draw outline circle
    cairo_set_source_rgba(cr, 1., 1., 1., 1.);
    cairo_arc(cr, g->box[k].x, g->box[k].y, 8. / zoom_scale, 0, 2. * M_PI);
    cairo_stroke(cr);
 
    // draw black dot
    cairo_set_source_rgba(cr, 0., 0., 0., 1.);
    cairo_arc(cr, g->box[k].x, g->box[k].y, 1.5 / zoom_scale, 0, 2. * M_PI);
    cairo_fill(cr);
  }
 
  // draw symmetry axes
  cairo_set_line_width(cr, 1.5 / zoom_scale);
  cairo_set_source_rgba(cr, 1., 1., 1., 1.);
  const point_t top_ideal = { 0.5f, 1.f };
  const point_t top = apply_homography(top_ideal, g->homography);
  const point_t bottom_ideal = { 0.5f, 0.f };
  const point_t bottom = apply_homography(bottom_ideal, g->homography);
  cairo_move_to(cr, top.x, top.y);
  cairo_line_to(cr, bottom.x, bottom.y);
  cairo_stroke(cr);
 
  const point_t left_ideal = { 0.f, 0.5f };
  const point_t left = apply_homography(left_ideal, g->homography);
  const point_t right_ideal = { 1.f, 0.5f };
  const point_t right = apply_homography(right_ideal, g->homography);
  cairo_move_to(cr, left.x, left.y);
  cairo_line_to(cr, right.x, right.y);
  cairo_stroke(cr);
 
  /* For debug : display center of the image and center of the ideal target
  point_t new_target_center = apply_homography(target_center, g->homography);
  cairo_set_source_rgba(cr, 1., 1., 1., 1.);
  cairo_arc(cr, new_target_center.x, new_target_center.y, 7., 0, 2. * M_PI);
  cairo_stroke(cr);
 
  cairo_set_source_rgba(cr, 0., 1., 1., 1.);
  cairo_arc(cr, 0.5 * wd, 0.5 * ht, 7., 0, 2. * M_PI);
  cairo_stroke(cr);
  */
  if(!g->checker || !g->checker->finished || !g->checker->values)
  {
    // no color data available, display a message
 
    const point_t target_center = { 0.5f, 0.5f };
    point_t new_target_center = apply_homography(target_center, g->homography);
 
    const char *msg = _("Error: No color data available for the selected chart.");
    cairo_set_font_size(cr, 20.0 / zoom_scale);
    cairo_text_extents_t extents;
    cairo_text_extents(cr, msg, &extents);
 
    // Draw a white rectangle behind the text
    cairo_set_source_rgba(cr, 1., 1., 1., 1.);
    cairo_rectangle(cr, 
            new_target_center.x - extents.width / 2.0 - 5.0 / zoom_scale, 
            new_target_center.y - extents.height / 2.0 - 5.0 / zoom_scale, 
            extents.width + 10.0 / zoom_scale, 
            extents.height + 10.0 / zoom_scale);
    cairo_fill(cr);
 
    // Draw the text in red
    cairo_set_source_rgba(cr, 1., 0., 0., 1.);
    cairo_select_font_face(cr, "roboto", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
    cairo_move_to(cr, new_target_center.x - extents.width / 2.0, new_target_center.y + extents.height / 2.0);
    cairo_show_text(cr, msg);
    return;
  }
 
  const float radius_x = g->checker->radius * hypotf(1.f, g->checker->ratio) * g->safety_margin;
  const float radius_y = radius_x / g->checker->ratio;
 
  for(size_t k = 0; k < g->checker->patches; k++)
  {
    // center of the patch in the ideal reference
    const point_t center = { g->checker->values[k].x, g->checker->values[k].y };
 
    // corners of the patch in the ideal reference
    const point_t corners[4] = { {center.x - radius_x, center.y - radius_y},
                                 {center.x + radius_x, center.y - radius_y},
                                 {center.x + radius_x, center.y + radius_y},
                                 {center.x - radius_x, center.y + radius_y} };
 
    // apply patch coordinates transform depending on perspective
    const point_t new_center = apply_homography(center, g->homography);
    // apply_homography_scaling gives a scaling of areas. we need to scale the
    // radius of the center circle so take a square root.
    const float scaling = sqrtf(apply_homography_scaling(center, g->homography));
    point_t new_corners[4];
    for(size_t c = 0; c < 4; c++) new_corners[c] = apply_homography(corners[c], g->homography);
 
    cairo_set_line_cap(cr, CAIRO_LINE_CAP_SQUARE);
    cairo_set_source_rgba(cr, 0., 0., 0., 1.);
    cairo_move_to(cr, new_corners[0].x, new_corners[0].y);
    cairo_line_to(cr, new_corners[1].x, new_corners[1].y);
    cairo_line_to(cr, new_corners[2].x, new_corners[2].y);
    cairo_line_to(cr, new_corners[3].x, new_corners[3].y);
    cairo_line_to(cr, new_corners[0].x, new_corners[0].y);
 
    if(g->delta_E_in)
    {
      // draw delta E feedback
      if(g->delta_E_in[k] > 2.3f)
      {
        // one diagonal if delta E > 3
        cairo_move_to(cr, new_corners[0].x, new_corners[0].y);
        cairo_line_to(cr, new_corners[2].x, new_corners[2].y);
      }
      if(g->delta_E_in[k] > 4.6f)
      {
        // the other diagonal if delta E > 6
        cairo_move_to(cr, new_corners[1].x, new_corners[1].y);
        cairo_line_to(cr, new_corners[3].x, new_corners[3].y);
      }
    }
 
    cairo_set_line_width(cr, 5.0 / zoom_scale);
    cairo_stroke_preserve(cr);
    cairo_set_line_width(cr, 2.0 / zoom_scale);
    cairo_set_source_rgba(cr, 1., 1., 1., 1.);
    cairo_stroke(cr);
 
    cairo_set_line_cap(cr, CAIRO_LINE_CAP_BUTT);
 
    dt_aligned_pixel_t RGB;
    dt_ioppr_lab_to_rgb_matrix(g->checker->values[k].Lab, RGB, work_profile->matrix_out_transposed, work_profile->lut_out,
                               work_profile->unbounded_coeffs_out, work_profile->lutsize,
                               work_profile->nonlinearlut);
 
    cairo_set_source_rgba(cr, RGB[0], RGB[1], RGB[2], 1.);
    cairo_arc(cr, new_center.x, new_center.y, 0.25 * (radius_x + radius_y) * scaling, 0, 2. * M_PI);
    cairo_fill(cr);
  }
}
 
static const dt_colorchecker_label_t *_checker_label_from_combobox(GtkWidget *combobox, GList *labels)
{
  const char *name = dt_bauhaus_combobox_get_entry(combobox, dt_bauhaus_combobox_get(combobox));
  if(IS_NULL_PTR(name)) return NULL;
 
  for(GList *l = g_list_first(labels); l; l = g_list_next(l))
  {
    const dt_colorchecker_label_t *label = (const dt_colorchecker_label_t *)l->data;
    if(!g_strcmp0(label->name, name)) return label;
  }
  return NULL;
}
 
static void _set_checker_from_labels(dt_iop_channelmixer_rgb_gui_data_t *g,
                                     const dt_colorchecker_label_t *checker_label,
                                     const dt_colorchecker_label_t *color_label)
{
  dt_colorchecker_cleanup(g->checker);
  g->checker = dt_get_color_checker(!IS_NULL_PTR(checker_label) ? checker_label->type : COLOR_CHECKER_XRITE_24_2000,
                                    !IS_NULL_PTR(checker_label) ? checker_label->path : NULL,
                                    !IS_NULL_PTR(color_label) ? color_label->path : NULL);
}
 
void color_list_visibility(dt_iop_module_t *self, const dt_colorchecker_label_t *checker_label)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  if(!IS_NULL_PTR(checker_label) && checker_label->type == COLOR_CHECKER_USER_REF)
    if(dt_bauhaus_combobox_get_entry(GTK_WIDGET(g->checkers_color_list), 0) != NULL)
    {
      gtk_widget_show(GTK_WIDGET(g->checkers_color_list));
      gtk_widget_hide(GTK_WIDGET(g->checker_msg));
    }
    else
    {
      gtk_widget_hide(GTK_WIDGET(g->checkers_color_list));
      gtk_widget_show_now(GTK_WIDGET(g->checker_msg));
    }
 
  else
  {
    gtk_widget_hide(GTK_WIDGET(g->checkers_color_list));
    gtk_widget_hide(GTK_WIDGET(g->checker_msg));
  }
}
 
void update_colorchecker_color_list(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  if(!g) return;
  if(!g->colorcheckers) return;
 
  // the CGATS reference values only apply to a user chart described by a .cht file
  const dt_colorchecker_label_t *checker_label = _checker_label_from_combobox(g->checkers_list, g->colorcheckers);
  if(IS_NULL_PTR(checker_label) || checker_label->type != COLOR_CHECKER_USER_REF) return;
 
  // find all CGATS files if not already done
  if(!g->n_color)
    g->n_color = dt_colorchecker_find_color(&(g->colorcheckers_all_color));
  // no CGATS files found, early return
  if(g->n_color == 0) return;
  
  // update the gui
  dt_bauhaus_combobox_clear(g->checkers_color_list);
  g_list_free(g->colorcheckers_color); // don't free_full because data pointers belong to g->colorcheckers_all_color
  g->colorcheckers_color = NULL;
 
  const int checker_patch_nb = checker_label->patch_nb;
  
  if(checker_patch_nb > 0)
  {
    for(GList *l = g_list_first(g->colorcheckers_all_color); l; l = g_list_next(l))
    {
      dt_colorchecker_label_t *cht_label = (dt_colorchecker_label_t *)l->data;
      // Filter out colorcheckers with different patch number.
      // A separate GList is required to associate the color checkers with their corresponding combobox item IDs.
      if(cht_label->patch_nb == checker_patch_nb)
      {
        dt_bauhaus_combobox_add(g->checkers_color_list, cht_label->name);
        g->colorcheckers_color = g_list_append(g->colorcheckers_color, cht_label);
      }
    }
  }
  dt_control_queue_redraw_widget(g->checkers_color_list);
}
 
void update_colorchecker_list(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g)) return;
 
  dt_colorchecker_label_list_cleanup(&(g->colorcheckers));
 
  dt_colorchecker_find(&(g->colorcheckers));
 
  // update the gui
  dt_bauhaus_combobox_clear(g->checkers_list);
  gboolean has_builtin_checker = FALSE;
  gboolean user_checker_separator_added = FALSE;
  for(GList *l = g_list_first(g->colorcheckers); l; l = g_list_next(l))
  {
    const dt_colorchecker_label_t *checker_data = (const dt_colorchecker_label_t*)l->data;
 
    if(checker_data->type < COLOR_CHECKER_USER_REF)
    {
      has_builtin_checker = TRUE;
    }
    else if(has_builtin_checker && !user_checker_separator_added)
    {
      dt_bauhaus_combobox_add_separator(g->checkers_list);
      user_checker_separator_added = TRUE;
    }
 
    dt_bauhaus_combobox_add(g->checkers_list, checker_data->name);
  }
}
 
static void optimize_changed_callback(GtkWidget *widget, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  const int i = dt_bauhaus_combobox_get(widget);
  dt_conf_set_int("darkroom/modules/channelmixerrgb/optimization", i);
 
  dt_iop_gui_enter_critical_section(self);
  g->optimization = i;
  dt_iop_gui_leave_critical_section(self);
}
 
static void checker_color_changed_callback(GtkWidget *widget, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  const dt_colorchecker_label_t *color_label = _checker_label_from_combobox(widget, g->colorcheckers_color);
  dt_conf_set_string("darkroom/modules/channelmixerrgb/colorchecker_color",
                     !IS_NULL_PTR(color_label) ? color_label->name : "");
 
  _set_checker_from_labels(g, _checker_label_from_combobox(g->checkers_list, g->colorcheckers), color_label);
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return;
 
  dt_iop_gui_enter_critical_section(self);
  g->profile_ready = FALSE;
  init_bounding_box(g, wd, ht);
  dt_iop_gui_leave_critical_section(self);
 
  dt_control_queue_redraw_center();
}
 
void checker_changed_callback(GtkWidget *widget, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  const dt_colorchecker_label_t *checker_label = _checker_label_from_combobox(widget, g->colorcheckers);
  dt_conf_set_string("darkroom/modules/channelmixerrgb/colorchecker",
                     !IS_NULL_PTR(checker_label) ? checker_label->name : "");
  dt_gui_freeze_begin();
  update_colorchecker_color_list(self);
  color_list_visibility(self, checker_label);
  dt_gui_freeze_end();
 
  _set_checker_from_labels(g, checker_label, _checker_label_from_combobox(g->checkers_color_list, g->colorcheckers_color));
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return;
 
  dt_iop_gui_enter_critical_section(self);
  g->profile_ready = FALSE;
  init_bounding_box(g, wd, ht);
  dt_iop_gui_leave_critical_section(self);
 
  dt_control_queue_redraw_center();
}
 
static void safety_changed_callback(GtkWidget *widget, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_iop_gui_enter_critical_section(self);
  g->safety_margin = dt_bauhaus_slider_get(widget);
  dt_iop_gui_leave_critical_section(self);
 
  dt_conf_set_float("darkroom/modules/channelmixerrgb/safety", g->safety_margin);
  dt_control_queue_redraw_center();
}
 
 
static void start_profiling_callback(GtkWidget *togglebutton, dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_request_focus(self);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(self->gui->off), TRUE);
 
  dt_develop_t *dev = self->dev;
  const float wd = dt_dev_roi_request_preview_width(dev);
  const float ht = dt_dev_roi_request_preview_height(dev);
  if(wd == 0.f || ht == 0.f) return;
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  g->is_profiling_started = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(g->cs.toggle));
 
  // init bounding box
  dt_iop_gui_enter_critical_section(self);
  init_bounding_box(g, wd, ht);
  dt_iop_gui_leave_critical_section(self);
 
  dt_control_queue_redraw_center();
}
 
static void run_profile_callback(GtkWidget *widget, GdkEventButton *event, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_iop_gui_enter_critical_section(self);
  g->run_profile = TRUE;
  dt_iop_set_cache_bypass(self, TRUE);
  dt_iop_gui_leave_critical_section(self);
  dt_dev_pixelpipe_resync_history_preview(self->dev);
}
 
static void run_validation_callback(GtkWidget *widget, GdkEventButton *event, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_iop_gui_enter_critical_section(self);
  g->run_validation = TRUE;
  dt_iop_set_cache_bypass(self, TRUE);
  dt_iop_gui_leave_critical_section(self);
  dt_dev_pixelpipe_resync_history_preview(self->dev);
}
 
static void commit_profile_callback(GtkWidget *widget, GdkEventButton *event, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  if(!g->profile_ready) return;
 
  dt_iop_gui_enter_critical_section(self);
 
  p->x = g->xy[0];
  p->y = g->xy[1];
  p->illuminant = DT_ILLUMINANT_CUSTOM;
  check_if_close_to_daylight(p->x, p->y, &p->temperature, NULL, NULL);
 
  p->red[0] = g->mix[0][0];
  p->red[1] = g->mix[0][1];
  p->red[2] = g->mix[0][2];
 
  p->green[0] = g->mix[1][0];
  p->green[1] = g->mix[1][1];
  p->green[2] = g->mix[1][2];
 
  p->blue[0] = g->mix[2][0];
  p->blue[1] = g->mix[2][1];
  p->blue[2] = g->mix[2][2];
 
  dt_iop_gui_leave_critical_section(self);
 
  dt_gui_freeze_begin();
  dt_bauhaus_combobox_set(g->illuminant, p->illuminant);
  dt_bauhaus_slider_set(g->temperature, p->temperature);
 
  dt_aligned_pixel_t xyY = { p->x, p->y, 1.f };
  dt_aligned_pixel_t Lch = { 0 };
  dt_xyY_to_Lch(xyY, Lch);
  dt_bauhaus_slider_set(g->illum_x, Lch[2] / M_PI * 180.f);
  dt_bauhaus_slider_set(g->illum_y, Lch[1]);
 
  dt_bauhaus_slider_set(g->scale_red_R, p->red[0]);
  dt_bauhaus_slider_set(g->scale_red_G, p->red[1]);
  dt_bauhaus_slider_set(g->scale_red_B, p->red[2]);
 
  dt_bauhaus_slider_set(g->scale_green_R, p->green[0]);
  dt_bauhaus_slider_set(g->scale_green_G, p->green[1]);
  dt_bauhaus_slider_set(g->scale_green_B, p->green[2]);
 
  dt_bauhaus_slider_set(g->scale_blue_R, p->blue[0]);
  dt_bauhaus_slider_set(g->scale_blue_G, p->blue[1]);
  dt_bauhaus_slider_set(g->scale_blue_B, p->blue[2]);
 
  dt_gui_freeze_end();
 
  gui_changed(self, NULL, NULL);
 
  dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] history commit source=commit_profile\n");
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void _develop_ui_pipe_finished_callback(gpointer instance, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  if(IS_NULL_PTR(g)) return;
  if(p->illuminant != DT_ILLUMINANT_DETECT_EDGES && p->illuminant != DT_ILLUMINANT_DETECT_SURFACES)
    return;
 
  dt_iop_gui_enter_critical_section(self);
  p->x = g->XYZ[0];
  p->y = g->XYZ[1];
  dt_iop_gui_leave_critical_section(self);
 
  check_if_close_to_daylight(p->x, p->y, &p->temperature, &p->illuminant, &p->adaptation);
 
  dt_gui_freeze_begin();
 
  dt_bauhaus_slider_set(g->temperature, p->temperature);
  dt_bauhaus_combobox_set(g->illuminant, p->illuminant);
  dt_bauhaus_combobox_set(g->adaptation, p->adaptation);
 
  const dt_aligned_pixel_t xyY = { p->x, p->y, 1.f };
  dt_aligned_pixel_t Lch;
  dt_xyY_to_Lch(xyY, Lch);
  dt_bauhaus_slider_set(g->illum_x, Lch[2] / M_PI * 180.f);
  dt_bauhaus_slider_set(g->illum_y, Lch[1]);
 
  update_illuminants(self);
  update_approx_cct(self);
  update_illuminant_color(self);
  dt_iop_channelmixer_shared_paint_temperature_slider(g->temperature, TEMP_MIN, TEMP_MAX);
 
  dt_gui_freeze_end();
 
  gui_changed(self, NULL, NULL);
 
  dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] history commit source=ui_pipe_finished\n");
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void _preview_pipe_finished_callback(gpointer instance, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_iop_gui_enter_critical_section(self);
  gtk_label_set_markup(GTK_LABEL(g->label_delta_E), g->delta_E_label_text);
  dt_iop_gui_leave_critical_section(self);
}
 
void commit_params(struct dt_iop_module_t *self, dt_iop_params_t *p1, dt_dev_pixelpipe_t *pipe,
                   dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)p1;
  dt_iop_channelmixer_rbg_data_t *d = (dt_iop_channelmixer_rbg_data_t *)piece->data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  d->version = p->version;
 
  float norm_R = 1.0f;
  if(p->normalize_R) norm_R = p->red[0] + p->red[1] + p->red[2];
 
  float norm_G = 1.0f;
  if(p->normalize_G) norm_G = p->green[0] + p->green[1] + p->green[2];
 
  float norm_B = 1.0f;
  if(p->normalize_B) norm_B = p->blue[0] + p->blue[1] + p->blue[2];
 
  float norm_sat = 0.0f;
  if(p->normalize_sat) norm_sat = (p->saturation[0] + p->saturation[1] + p->saturation[2]) / 3.f;
 
  float norm_light = 0.0f;
  if(p->normalize_light) norm_light = (p->lightness[0] + p->lightness[1] + p->lightness[2]) / 3.f;
 
  float norm_grey = p->grey[0] + p->grey[1] + p->grey[2];
  d->apply_grey = (p->grey[0] != 0.f) || (p->grey[1] != 0.f) || (p->grey[2] != 0.f);
  if(!p->normalize_grey || norm_grey == 0.f) norm_grey = 1.f;
 
  for(int i = 0; i < 3; i++)
  {
    d->MIX[0][i] = p->red[i] / norm_R;
    d->MIX[1][i] = p->green[i] / norm_G;
    d->MIX[2][i] = p->blue[i] / norm_B;
    d->saturation[i] = -p->saturation[i] + norm_sat;
    d->lightness[i] = p->lightness[i] - norm_light;
    d->grey[i] = p->grey[i] / norm_grey; // = NaN if (norm_grey == 0.f) but we don't care since (d->apply_grey == FALSE)
  }
 
  if(p->version == CHANNELMIXERRGB_V_1)
  {
    // for the v1 saturation algo, the effect of R and B coeffs is reversed
    d->saturation[0] = -p->saturation[2] + norm_sat;
    d->saturation[2] = -p->saturation[0] + norm_sat;
  }
 
  // just in case compiler feels clever and uses SSE 4x1 dot product
  d->saturation[CHANNEL_SIZE - 1] = 0.0f;
  d->lightness[CHANNEL_SIZE - 1] = 0.0f;
  d->grey[CHANNEL_SIZE - 1] = 0.0f;
 
  d->adaptation = p->adaptation;
  d->clip = p->clip;
  d->gamut = (p->gamut == 0.f) ? p->gamut : 1.f / p->gamut;
 
  // find x y coordinates of illuminant for CIE 1931 2° observer
  float x = p->x;
  float y = p->y;
  dt_aligned_pixel_t custom_wb;
  // Pipeline thread: source temperature's WB from the per-piece descriptor propagated in pipe order
  // (temperature writes piece->dsc_out.temperature.coeffs upstream), NOT from dev->proxy.
  _custom_wb_from_coeffs(self, piece->dsc_in.temperature.coeffs, custom_wb);
  illuminant_to_xy(p->illuminant, &(self->dev->image_storage), custom_wb, &x, &y, p->temperature, p->illum_fluo, p->illum_led);
 
  // if illuminant is set as camera, x and y are set on-the-fly at commit time, so we need to set adaptation too
  if(p->illuminant == DT_ILLUMINANT_CAMERA)
    check_if_close_to_daylight(x, y, NULL, NULL, &(d->adaptation));
 
  d->illuminant_type = p->illuminant;
 
  // Convert illuminant from xyY to XYZ
  dt_aligned_pixel_t XYZ;
  illuminant_xy_to_XYZ(x, y, XYZ);
 
  // Convert illuminant from XYZ to Bradford modified LMS
  dt_store_simd_aligned(d->illuminant, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ), d->adaptation));
  d->illuminant[3] = 0.f;
 
  dt_iop_fmt_log(self, "commit: class=%s matrix_supported=%d illuminant=%d adaptation=%d custom_wb=[%.4f %.4f %.4f %.4f] xy=[%.4f %.4f]",
                 dt_image_pipe_class_name(dt_image_pipe_class(&pipe->dev->image_storage)),
                 dt_image_is_matrix_correction_supported(&pipe->dev->image_storage),
                 p->illuminant, d->adaptation, custom_wb[0], custom_wb[1], custom_wb[2], custom_wb[3], x, y);
 
  //fprintf(stdout, "illuminant: %i\n", p->illuminant);
  //fprintf(stdout, "x: %f, y: %f\n", x, y);
  //fprintf(stdout, "X: %f - Y: %f - Z: %f\n", XYZ[0], XYZ[1], XYZ[2]);
  //fprintf(stdout, "L: %f - M: %f - S: %f\n", d->illuminant[0], d->illuminant[1], d->illuminant[2]);
 
  // blue compensation for Bradford transform = (test illuminant blue / reference illuminant blue)^0.0834
  // reference illuminant is hard-set D50 for darktable's pipeline
  // test illuminant is user params
  d->p = powf(0.818155f / d->illuminant[2], 0.0834f);
 
  // Disable OpenCL path if we are in any kind of diagnose mode (only C path has diagnostics)
  if(self->dev->gui_attached && g)
  {
    if( (g->run_profile && pipe->type == DT_DEV_PIXELPIPE_PREVIEW) || // color checker extraction mode
        (g->run_validation && pipe->type == DT_DEV_PIXELPIPE_PREVIEW) || // delta E validation
        ( (d->illuminant_type == DT_ILLUMINANT_DETECT_EDGES ||
           d->illuminant_type == DT_ILLUMINANT_DETECT_SURFACES ) && // WB extraction mode
           pipe->type == DT_DEV_PIXELPIPE_FULL ) )
    {
      piece->process_cl_ready = 0;
 
      // Same reason, and the one nobody wrote down: all three modes consume the WHOLE frame in a
      // single call -- the two colour-checker paths address it with chart-box coordinates, and
      // auto_detect_WB() averages it. Tiling calls process() once per tile with a tile-local
      // roi_in, so the chart box would be applied to a fragment and whichever tile ran last would
      // win. Whether that happens is a runtime memory decision
      // (dt_tiling_piece_fits_host_memory(), which reads dt_get_available_mem() and the pixelpipe
      // cache's largest free run), so it shows up on one machine and not another.
      piece->process_tiling_ready = 0;
    }
  }
}
 
 
static void update_illuminants(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  if(p->adaptation == DT_ADAPTATION_RGB || p->adaptation == DT_ADAPTATION_LAST)
  {
    // user disabled CAT at all, hide everything and exit
    gtk_widget_set_visible(g->illuminant, FALSE);
    gtk_widget_set_visible(g->illum_color, FALSE);
    gtk_widget_set_visible(g->approx_cct, FALSE);
    gtk_widget_set_visible(g->color_picker, FALSE);
    gtk_widget_set_visible(g->temperature, FALSE);
    gtk_widget_set_visible(g->illum_fluo, FALSE);
    gtk_widget_set_visible(g->illum_led, FALSE);
    gtk_widget_set_visible(g->illum_x, FALSE);
    gtk_widget_set_visible(g->illum_y, FALSE);
    return;
  }
  else
  {
    // set everything visible again and carry on
    gtk_widget_set_visible(g->illuminant, TRUE);
    gtk_widget_set_visible(g->illum_color, TRUE);
    gtk_widget_set_visible(g->approx_cct, TRUE);
    gtk_widget_set_visible(g->color_picker, TRUE);
    gtk_widget_set_visible(g->temperature, TRUE);
    gtk_widget_set_visible(g->illum_fluo, TRUE);
    gtk_widget_set_visible(g->illum_led, TRUE);
    gtk_widget_set_visible(g->illum_x, TRUE);
  }
 
  // Display only the relevant sliders
  switch(p->illuminant)
  {
    case DT_ILLUMINANT_PIPE:
    case DT_ILLUMINANT_A:
    case DT_ILLUMINANT_E:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_D:
    case DT_ILLUMINANT_BB:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, TRUE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_F:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, TRUE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_LED:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, TRUE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_CUSTOM:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, TRUE);
      gtk_widget_set_visible(g->illum_y, TRUE);
      break;
    }
    case DT_ILLUMINANT_CAMERA:
    {
      gtk_widget_set_visible(g->adaptation, TRUE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_DETECT_EDGES:
    case DT_ILLUMINANT_DETECT_SURFACES:
    {
      gtk_widget_set_visible(g->adaptation, FALSE);
      gtk_widget_set_visible(g->temperature, FALSE);
      gtk_widget_set_visible(g->illum_fluo, FALSE);
      gtk_widget_set_visible(g->illum_led, FALSE);
      gtk_widget_set_visible(g->illum_x, FALSE);
      gtk_widget_set_visible(g->illum_y, FALSE);
      break;
    }
    case DT_ILLUMINANT_LAST:
    default:
    {
      break;
    }
  }
}
 
static void update_xy_color(dt_iop_module_t *self)
{
  // update the fill background color of x, y sliders
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  if(IS_NULL_PTR(g) || IS_NULL_PTR(p) || IS_NULL_PTR(g->illum_x) || IS_NULL_PTR(g->illum_y)) return;
 
  // Varies x in range around current y param
  for(int i = 0; i < DT_BAUHAUS_SLIDER_MAX_STOPS; i++)
  {
    const float stop = ((float)i / (float)(DT_BAUHAUS_SLIDER_MAX_STOPS - 1));
    const float x = stop * ILLUM_X_MAX;
    dt_aligned_pixel_t RGB = { 0 };
 
    dt_aligned_pixel_t Lch = { 100.f, 50.f, x / 180.f * M_PI };
    dt_aligned_pixel_t xyY = { 0 };
    dt_Lch_to_xyY(Lch, xyY);
    illuminant_xy_to_RGB(xyY[0], xyY[1], RGB);
    dt_bauhaus_slider_set_stop(g->illum_x, stop, RGB[0], RGB[1], RGB[2]);
 
    const float y = stop * ILLUM_Y_MAX / 2.0f;
 
    // Find current hue
    const dt_aligned_pixel_t xyY2 = { p->x, p->y, 1.f };
    dt_xyY_to_Lch(xyY2, Lch);
 
    // Replace chroma by current step
    Lch[0] = 75.f;
    Lch[1] = y;
 
    // Go back to xyY
    dt_Lch_to_xyY(Lch, xyY);
    illuminant_xy_to_RGB(xyY[0], xyY[1], RGB);
    dt_bauhaus_slider_set_stop(g->illum_y, stop, RGB[0], RGB[1], RGB[2]);
  }
 
  gtk_widget_queue_draw(g->illum_x);
  gtk_widget_queue_draw(g->illum_y);
}
 
static void paint_hue(dt_iop_module_t *self)
{
  // update the fill background color of LCh sliders
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  const float hue = dt_bauhaus_slider_get(g->hue_spot);
 
  for(int i = 0; i < DT_BAUHAUS_SLIDER_MAX_STOPS; i++)
  {
    const float stop = ((float)i / (float)(DT_BAUHAUS_SLIDER_MAX_STOPS - 1));
    dt_aligned_pixel_t RGB = { 0 }, Lab = { 0 }, XYZ = { 0 };
 
    const dt_aligned_pixel_t Lch_hue = { 67.f, 96.f, (stop * HUE_MAX) / 360.f};
 
    dt_LCH_2_Lab(Lch_hue, Lab);
    dt_Lab_to_XYZ(Lab, XYZ);
    dt_XYZ_to_sRGB(XYZ, RGB);
 
    dt_bauhaus_slider_set_stop(g->hue_spot, stop, RGB[0], RGB[1], RGB[2]);
 
    const dt_aligned_pixel_t Lch_lightness = { stop * LIGHTNESS_MAX, 0.f, 0. };
 
    dt_LCH_2_Lab(Lch_lightness, Lab);
    dt_Lab_to_XYZ(Lab, XYZ);
    dt_XYZ_to_sRGB(XYZ, RGB);
 
    dt_bauhaus_slider_set_stop(g->lightness_spot, stop, RGB[0], RGB[1], RGB[2]);
 
    const dt_aligned_pixel_t Lch_chroma = { 50., stop * CHROMA_MAX, hue / 360.f };
 
    dt_LCH_2_Lab(Lch_chroma, Lab);
    dt_Lab_to_XYZ(Lab, XYZ);
    dt_XYZ_to_sRGB(XYZ, RGB);
 
    dt_bauhaus_slider_set_stop(g->chroma_spot, stop, RGB[0], RGB[1], RGB[2]);
  }
 
  gtk_widget_queue_draw(g->hue_spot);
  gtk_widget_queue_draw(g->lightness_spot);
  gtk_widget_queue_draw(g->chroma_spot);
  gtk_widget_queue_draw(g->target_spot);
}
 
 
static gboolean _channelmixerrgb_sync_primaries_from_params(dt_iop_module_t *self, float *error)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  const dt_iop_channelmixer_rgb_params_t *const p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *const widgets[9]
      = { g->primaries_achromatic_hue, g->primaries_achromatic_purity, g->primaries_red_hue,
          g->primaries_red_purity, g->primaries_green_hue, g->primaries_green_purity,
          g->primaries_blue_hue, g->primaries_blue_purity, g->primaries_gain };
  dt_iop_channelmixer_rgb_primaries_params_t primaries;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
  const float rows[3][3] = { { p->red[0], p->red[1], p->red[2] },
                             { p->green[0], p->green[1], p->green[2] },
                             { p->blue[0], p->blue[1], p->blue[2] } };
  const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
  float M[3][3] = { { 0.f } };
  float roundtrip[3][3] = { { 0.f } };
 
  if(!dt_iop_channelmixer_shared_get_matrix(rows, normalize, FALSE, M)) return FALSE;
  if(!dt_iop_channelmixer_shared_primaries_from_matrix(basis, M, &primaries)) return FALSE;
  if(!dt_iop_channelmixer_shared_primaries_to_matrix(basis, &primaries, roundtrip)) return FALSE;
 
  const float roundtrip_error = dt_iop_channelmixer_shared_roundtrip_error(M, roundtrip);
  if(!IS_NULL_PTR(error)) *error = roundtrip_error;
 
  dt_gui_freeze_begin();
  dt_iop_channelmixer_shared_primaries_to_sliders(&primaries, widgets);
  dt_gui_freeze_end();
  return isfinite(roundtrip_error) && roundtrip_error <= DT_CHANNELMIXERRGB_SIMPLE_EPS;
}
 
static void _channelmixerrgb_update_primaries_colors(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_work_profile_info(self->dev->pipe);
  const dt_iop_order_iccprofile_info_t *const display_profile
      = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
  GtkWidget *const widgets[9]
      = { g->primaries_achromatic_hue, g->primaries_achromatic_purity, g->primaries_red_hue,
          g->primaries_red_purity, g->primaries_green_hue, g->primaries_green_purity,
          g->primaries_blue_hue, g->primaries_blue_purity, g->primaries_gain };
  dt_iop_channelmixer_rgb_primaries_params_t primaries;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
 
  dt_iop_channelmixer_shared_primaries_from_sliders(widgets, &primaries);
  dt_iop_channelmixer_shared_paint_primaries_sliders(p->adaptation, work_profile, display_profile, basis, &primaries,
                                                     widgets);
}
 
static gboolean _channelmixerrgb_white_preserving_widgets(const dt_iop_channelmixer_rgb_gui_data_t *const g,
                                                          GtkWidget *widgets[6])
{
  widgets[0] = g->white_preserving_red_rotation;
  widgets[1] = g->white_preserving_red_saturation;
  widgets[2] = g->white_preserving_green_rotation;
  widgets[3] = g->white_preserving_green_saturation;
  widgets[4] = g->white_preserving_blue_rotation;
  widgets[5] = g->white_preserving_blue_saturation;
 
  for(int widget = 0; widget < 6; widget++)
    if(IS_NULL_PTR(widgets[widget])) return FALSE;
 
  return TRUE;
}
 
static gboolean _channelmixerrgb_sync_white_preserving_from_params(dt_iop_module_t *self, float *error)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  const dt_iop_channelmixer_rgb_params_t *const p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *widgets[6] = { NULL };
  dt_iop_channelmixer_rgb_white_preserving_params_t white_preserving;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
  const float rows[3][3] = { { p->red[0], p->red[1], p->red[2] },
                             { p->green[0], p->green[1], p->green[2] },
                             { p->blue[0], p->blue[1], p->blue[2] } };
  const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
  float M[3][3] = { { 0.f } };
  float roundtrip[3][3] = { { 0.f } };
 
  if(!_channelmixerrgb_white_preserving_widgets(g, widgets)) return FALSE;
  if(!dt_iop_channelmixer_shared_get_matrix(rows, normalize, FALSE, M)) return FALSE;
  if(!dt_iop_channelmixer_shared_white_preserving_from_matrix(basis, M, &white_preserving)) return FALSE;
  if(!dt_iop_channelmixer_shared_white_preserving_to_matrix(basis, &white_preserving, roundtrip)) return FALSE;
 
  const float roundtrip_error = dt_iop_channelmixer_shared_roundtrip_error_relative(M, roundtrip);
  if(!IS_NULL_PTR(error)) *error = roundtrip_error;
 
  dt_gui_freeze_begin();
  dt_iop_channelmixer_shared_white_preserving_to_sliders(&white_preserving, widgets);
  dt_gui_freeze_end();
  return isfinite(roundtrip_error) && roundtrip_error <= DT_CHANNELMIXERRGB_SIMPLE_EPS;
}
 
static void _channelmixerrgb_update_white_preserving_colors(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_work_profile_info(self->dev->pipe);
  const dt_iop_order_iccprofile_info_t *const display_profile
      = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
  GtkWidget *widgets[6] = { NULL };
  dt_iop_channelmixer_rgb_white_preserving_params_t white_preserving;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
 
  if(!_channelmixerrgb_white_preserving_widgets(g, widgets)) return;
 
  dt_iop_channelmixer_shared_white_preserving_from_sliders(widgets, &white_preserving);
  dt_iop_channelmixer_shared_paint_white_preserving_sliders(p->adaptation, work_profile, display_profile, basis,
                                                            &white_preserving, widgets);
}
 
static void _convert_GUI_colors(dt_iop_channelmixer_rgb_params_t *p,
                                const struct dt_iop_order_iccprofile_info_t *const work_profile,
                                const struct dt_iop_order_iccprofile_info_t *const display_profile,
                                const dt_aligned_pixel_t LMS, dt_aligned_pixel_t RGB)
{
  dt_aligned_pixel_t work_rgb = { LMS[0], LMS[1], LMS[2], 0.f };
 
  if(p->adaptation != DT_ADAPTATION_RGB)
  {
    convert_any_LMS_to_RGB(LMS, work_rgb, p->adaptation);
  }
  else
  {
    for(size_t c = 0; c < 3; c++) work_rgb[c] = LMS[c];
  }
 
  dt_iop_channelmixer_shared_work_rgb_to_display(work_rgb, work_profile, display_profile, RGB);
}
 
static void _update_RGB_slider_stop(dt_iop_channelmixer_rgb_params_t *p,
                                    const struct dt_iop_order_iccprofile_info_t *const work_profile,
                                    const struct dt_iop_order_iccprofile_info_t *const display_profile,
                                    GtkWidget *w, float stop, float c, float r, float g, float b)
{
  const dt_aligned_pixel_t LMS = { 0.5f * (c * r + 1 - r),
                                   0.5f * (c * g + 1 - g),
                                   0.5f * (c * b + 1 - b)};
  dt_aligned_pixel_t RGB_t = { 0.5f };
  _convert_GUI_colors(p, work_profile, display_profile, LMS, RGB_t);
  dt_bauhaus_slider_set_stop(w, stop, RGB_t[0], RGB_t[1], RGB_t[2]);
}
 
static void _update_RGB_colors(dt_iop_module_t *self, float r, float g, float b, gboolean normalize, float *a,
                               GtkWidget *w_r, GtkWidget *w_g, GtkWidget *w_b)
{
  // update the fill background color of x, y sliders
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const struct dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_work_profile_info(self->dev->pipe);
  const struct dt_iop_order_iccprofile_info_t *const display_profile = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
 
  // scale params if needed
  dt_aligned_pixel_t RGB = { a[0], a[1], a[2] };
 
  if(normalize)
  {
    const float sum = RGB[0] + RGB[1] + RGB[2];
    if(sum != 0.f) for(int c = 0; c < 3; c++) RGB[c] /= sum;
  }
 
  for(int i = 0; i < DT_BAUHAUS_SLIDER_MAX_STOPS; i++)
  {
    const float stop = ((float)i / (float)(DT_BAUHAUS_SLIDER_MAX_STOPS - 1));
    // Use the hard bounds of the sliders; drawing will take into account the possible soft rescaling
    const float range_x = COLOR_MAX - COLOR_MIN;
 
    const float x = COLOR_MIN + stop * range_x;
 
    _update_RGB_slider_stop(p, work_profile, display_profile, w_r, stop, x      + RGB[1] + RGB[2], r, g, b);
    _update_RGB_slider_stop(p, work_profile, display_profile, w_g, stop, RGB[0] + x      + RGB[2], r, g, b);
    _update_RGB_slider_stop(p, work_profile, display_profile, w_b, stop, RGB[0] + RGB[1] + x     , r, g, b);
  }
 
  gtk_widget_queue_draw(w_r);
  gtk_widget_queue_draw(w_b);
  gtk_widget_queue_draw(w_g);
}
 
static gboolean _channelmixerrgb_sync_simple_from_params(dt_iop_module_t *self, float *error)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *const widgets[6]
      = { g->simple_theta, g->simple_psi, g->simple_stretch_1, g->simple_stretch_2, g->simple_coupling_1,
          g->simple_coupling_2 };
  const float rows[3][3] = { { p->red[0], p->red[1], p->red[2] },
                             { p->green[0], p->green[1], p->green[2] },
                             { p->blue[0], p->blue[1], p->blue[2] } };
  const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
  float M[3][3] = { { 0.f } };
  float roundtrip[3][3] = { { 0.f } };
  dt_iop_channelmixer_rgb_simple_params_t simple;
 
  if(!IS_NULL_PTR(error)) *error = INFINITY;
  if(!dt_iop_channelmixer_shared_rows_are_normalized(normalize)) return FALSE;
  if(!dt_iop_channelmixer_shared_get_matrix(rows, normalize, FALSE, M)) return FALSE;
 
  dt_iop_channelmixer_shared_simple_from_matrix(M, &simple);
  dt_iop_channelmixer_shared_simple_to_matrix(&simple, roundtrip);
 
  const float roundtrip_error = dt_iop_channelmixer_shared_roundtrip_error(M, roundtrip);
  if(!IS_NULL_PTR(error)) *error = roundtrip_error;
 
  dt_gui_freeze_begin();
  dt_iop_channelmixer_shared_simple_to_sliders(&simple, widgets);
  dt_gui_freeze_end();
 
  return isfinite(roundtrip_error) && roundtrip_error <= DT_CHANNELMIXERRGB_SIMPLE_EPS;
}
 
static void _channelmixerrgb_update_simple_colors(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  const dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const dt_iop_order_iccprofile_info_t *const work_profile = dt_ioppr_get_pipe_work_profile_info(self->dev->pipe);
  const dt_iop_order_iccprofile_info_t *const display_profile
      = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
  GtkWidget *const widgets[6]
      = { g->simple_theta, g->simple_psi, g->simple_stretch_1, g->simple_stretch_2, g->simple_coupling_1,
          g->simple_coupling_2 };
  dt_iop_channelmixer_rgb_simple_params_t simple;
 
  dt_iop_channelmixer_shared_simple_from_sliders(widgets, &simple);
  dt_iop_channelmixer_shared_paint_simple_sliders(p->adaptation, work_profile, display_profile, &simple, widgets);
}
 
 
static void update_illuminant_color(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  if(IS_NULL_PTR(g)) return;
 
  if(!IS_NULL_PTR(g->illum_color))
    gtk_widget_queue_draw(g->illum_color);
 
  update_xy_color(self);
}
 
static gboolean illuminant_color_draw(GtkWidget *widget, cairo_t *crf, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  // Init
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;
  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
 
  // Margins
  const float margin = 2. * DT_PIXEL_APPLY_DPI(1.5);
  width -= INTERNAL_PADDING;
  height -= 2 * margin;
 
  // Paint illuminant color - we need to recompute it in full in case camera RAW is chosen
  float x = p->x;
  float y = p->y;
  dt_aligned_pixel_t RGB = { 0 };
  dt_aligned_pixel_t custom_wb;
  get_white_balance_coeff(self, custom_wb);
  illuminant_to_xy(p->illuminant, &(self->dev->image_storage), custom_wb,
                   &x, &y, p->temperature, p->illum_fluo, p->illum_led);
  illuminant_xy_to_RGB(x, y, RGB);
  cairo_set_source_rgb(cr, RGB[0], RGB[1], RGB[2]);
  cairo_rectangle(cr, INNER_PADDING, margin, width, height);
  cairo_fill(cr);
 
  // Clean
  cairo_stroke(cr);
  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);
  return TRUE;
}
 
static gboolean target_color_draw(GtkWidget *widget, cairo_t *crf, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  // Init
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;
  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
 
  // Margins
  const float margin = 2. * DT_PIXEL_APPLY_DPI(1.5);
  width -= INTERNAL_PADDING;
  height -= 2 * margin;
 
  // Paint target color
  dt_aligned_pixel_t RGB = { 0 };
  dt_aligned_pixel_t Lch = { 0 };
  dt_aligned_pixel_t Lab = { 0 };
  dt_aligned_pixel_t XYZ = { 0 };
  Lch[0] = dt_bauhaus_slider_get(g->lightness_spot);
  Lch[1] = dt_bauhaus_slider_get(g->chroma_spot);
  Lch[2] = dt_bauhaus_slider_get(g->hue_spot) / 360.f;
  dt_LCH_2_Lab(Lch, Lab);
  dt_Lab_to_XYZ(Lab, XYZ);
  dt_XYZ_to_sRGB(XYZ, RGB);
 
  cairo_set_source_rgb(cr, RGB[0], RGB[1], RGB[2]);
  cairo_rectangle(cr, INNER_PADDING, margin, width, height);
  cairo_fill(cr);
 
  // Clean
  cairo_stroke(cr);
  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);
  return TRUE;
}
 
static gboolean origin_color_draw(GtkWidget *widget, cairo_t *crf, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  // Init
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;
  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
 
  // Margins
  const float margin = 2. * DT_PIXEL_APPLY_DPI(1.5);
  width -= INTERNAL_PADDING;
  height -= 2 * margin;
 
  cairo_set_source_rgb(cr, g->spot_RGB[0], g->spot_RGB[1], g->spot_RGB[2]);
  cairo_rectangle(cr, INNER_PADDING, margin, width, height);
  cairo_fill(cr);
 
  // Clean
  cairo_stroke(cr);
  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);
  return TRUE;
}
 
static void update_approx_cct(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
 
  float x = p->x;
  float y = p->y;
  dt_aligned_pixel_t custom_wb;
  get_white_balance_coeff(self, custom_wb);
  illuminant_to_xy(p->illuminant, &(self->dev->image_storage), custom_wb, &x, &y, p->temperature, p->illum_fluo, p->illum_led);
 
  dt_illuminant_t test_illuminant;
  float t = 5000.f;
  check_if_close_to_daylight(x, y, &t, &test_illuminant, NULL);
 
  gchar *str;
  if(t > 1667.f && t < 25000.f)
  {
    if(test_illuminant == DT_ILLUMINANT_D)
    {
      str = g_strdup_printf(_("CCT: %.0f K (daylight)"), t);
      gtk_widget_set_tooltip_text(GTK_WIDGET(g->approx_cct),
                                  _("approximated correlated color temperature.\n"
                                    "this illuminant can be accurately modeled by a daylight spectrum,\n"
                                    "so its temperature is relevant and meaningful with a D illuminant."));
    }
    else if(test_illuminant == DT_ILLUMINANT_BB)
    {
      str = g_strdup_printf(_("CCT: %.0f K (black body)"), t);
      gtk_widget_set_tooltip_text(GTK_WIDGET(g->approx_cct),
                                  _("approximated correlated color temperature.\n"
                                    "this illuminant can be accurately modeled by a black body spectrum,\n"
                                    "so its temperature is relevant and meaningful with a Planckian illuminant."));
    }
    else
    {
      str = g_strdup_printf(_("CCT: %.0f K (invalid)"), t);
      gtk_widget_set_tooltip_text(GTK_WIDGET(g->approx_cct),
                                  _("approximated correlated color temperature.\n"
                                    "this illuminant cannot be accurately modeled by a daylight or black body spectrum,\n"
                                    "so its temperature is not relevant and meaningful and you need to use a custom illuminant."));
    }
  }
  else
  {
    str = g_strdup_printf(_("CCT: undefined"));
    gtk_widget_set_tooltip_text(GTK_WIDGET(g->approx_cct),
                                _("the approximated correlated color temperature\n"
                                  "cannot be computed at all so you need to use a custom illuminant."));
  }
  gtk_label_set_text(GTK_LABEL(g->approx_cct), str);
  dt_free(str);
}
 
 
static void illum_xy_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_aligned_pixel_t Lch = { 0 };
  Lch[0] = 100.f;
  Lch[2] = dt_bauhaus_slider_get(g->illum_x) / 180. * M_PI;
  Lch[1] = dt_bauhaus_slider_get(g->illum_y);
 
  dt_aligned_pixel_t xyY = { 0 };
  dt_Lch_to_xyY(Lch, xyY);
  p->x = xyY[0];
  p->y = xyY[1];
 
  float t = xy_to_CCT(p->x, p->y);
  // xy_to_CCT is valid only above 3000 K
  if(t < 3000.f) t = CCT_reverse_lookup(p->x, p->y);
  p->temperature = t;
 
  dt_gui_freeze_begin();
  dt_bauhaus_slider_set(g->temperature, p->temperature);
  update_approx_cct(self);
  update_illuminant_color(self);
  dt_iop_channelmixer_shared_paint_temperature_slider(g->temperature, TEMP_MIN, TEMP_MAX);
  dt_gui_freeze_end();
 
  dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] history commit source=illum_xy_callback slider=%p\n",
           (void *)slider);
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
void init_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  piece->data = dt_calloc_align(sizeof(dt_iop_channelmixer_rbg_data_t));
  piece->data_size = sizeof(dt_iop_channelmixer_rbg_data_t);
}
 
void cleanup_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  self->dev->proxy.chroma_adaptation = NULL;
  dt_free_align(piece->data);
  piece->data = NULL;
}
 
void gui_reset(dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  g->is_profiling_started = FALSE;
  dt_iop_color_picker_reset(self, TRUE);
  gui_changed(self, NULL, NULL);
}
 
void gui_update(struct dt_iop_module_t *self)
{
  dt_iop_module_t *module = (dt_iop_module_t *)self;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)module->params;
  float simple_error = INFINITY;
  float primaries_error = INFINITY;
  float white_preserving_error = INFINITY;
 
  dt_iop_color_picker_reset(self, TRUE);
 
  /* Restoring GUI state from params must not re-enter widget callbacks.
     Channelmixer's spot/color widgets can otherwise rerun auto-picking while
     a history refresh is already in flight, which feeds TOP_CHANGED/full-pipe
     loops when the picker is active. */
  dt_gui_freeze_begin();
 
  // always reset the mode the correct
  dt_bauhaus_combobox_set(g->spot_mode, DT_SPOT_MODE_CORRECT);
 
  // get the saved params
  dt_iop_gui_enter_critical_section(self);
 
  gboolean use_mixing = TRUE;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/use_mixing"))
    use_mixing = dt_conf_get_bool("darkroom/modules/channelmixerrgb/use_mixing");
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->use_mixing), use_mixing);
 
  float lightness = 50.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/lightness"))
    lightness = dt_conf_get_float("darkroom/modules/channelmixerrgb/lightness");
  dt_bauhaus_slider_set(g->lightness_spot, lightness);
 
  float hue = 0.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/hue"))
    hue = dt_conf_get_float("darkroom/modules/channelmixerrgb/hue");
  dt_bauhaus_slider_set(g->hue_spot, hue);
 
  float chroma = 0.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/chroma"))
    chroma = dt_conf_get_float("darkroom/modules/channelmixerrgb/chroma");
  dt_bauhaus_slider_set(g->chroma_spot, chroma);
 
  dt_iop_gui_leave_critical_section(self);
 
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->clip), p->clip);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_R), p->normalize_R);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_G), p->normalize_G);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_B), p->normalize_B);
 
  const gboolean simple_ok = _channelmixerrgb_sync_simple_from_params(self, &simple_error);
  const gboolean primaries_ok = _channelmixerrgb_sync_primaries_from_params(self, &primaries_error);
  const gboolean white_preserving_ok
      = _channelmixerrgb_sync_white_preserving_from_params(self, &white_preserving_error);
  const dt_iop_channelmixer_rgb_mixer_mode_t requested_mode
      = dt_conf_key_exists(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF)
            ? dt_conf_get_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF)
            : DT_CHANNELMIXERRGB_MIXER_COMPLETE;
  const dt_iop_channelmixer_rgb_mixer_mode_t mixer_mode
      = requested_mode == DT_CHANNELMIXERRGB_MIXER_SIMPLE && simple_ok
            ? DT_CHANNELMIXERRGB_MIXER_SIMPLE
            : requested_mode == DT_CHANNELMIXERRGB_MIXER_PRIMARIES && primaries_ok
                  ? DT_CHANNELMIXERRGB_MIXER_PRIMARIES
                  : requested_mode == DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING && white_preserving_ok
                        ? DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING
                        : DT_CHANNELMIXERRGB_MIXER_COMPLETE;
  dt_bauhaus_combobox_set(g->mixer_mode, mixer_mode);
  _channelmixerrgb_set_mixer_mode(g, mixer_mode);
 
  if(p->version != CHANNELMIXERRGB_V_3)
    dt_bauhaus_combobox_set(g->saturation_version, p->version);
  else
    gtk_widget_hide(GTK_WIDGET(g->saturation_version));
 
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_sat), p->normalize_sat);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_light), p->normalize_light);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_grey), p->normalize_grey);
 
  dt_iop_gui_enter_critical_section(self);
 
  // Restore both selections by name: the chart list is rebuilt from scratch here, and the
  // stored name has to survive a built-in chart being added or a .cht file appearing.
  // The color list is filtered by the selected chart, so the chart combo box comes first.
  update_colorchecker_list(self);
 
  gchar *selected_checker = dt_conf_get_string("darkroom/modules/channelmixerrgb/colorchecker");
  if(!dt_bauhaus_combobox_set_from_text(g->checkers_list, selected_checker))
    dt_bauhaus_combobox_set(g->checkers_list, 0);
  dt_free(selected_checker);
 
  const dt_colorchecker_label_t *checker_label = _checker_label_from_combobox(g->checkers_list, g->colorcheckers);
 
  update_colorchecker_color_list(self);
 
  gchar *selected_color = dt_conf_get_string("darkroom/modules/channelmixerrgb/colorchecker_color");
  if(!dt_bauhaus_combobox_set_from_text(g->checkers_color_list, selected_color))
    dt_bauhaus_combobox_set(g->checkers_color_list, 0);
  dt_free(selected_color);
 
  _set_checker_from_labels(g, checker_label,
                           _checker_label_from_combobox(g->checkers_color_list, g->colorcheckers_color));
 
  color_list_visibility(self, checker_label);
 
  const int j = dt_conf_get_int("darkroom/modules/channelmixerrgb/optimization");
  dt_bauhaus_combobox_set(g->optimize, j);
  g->optimization = j;
 
  g->safety_margin = dt_conf_get_float("darkroom/modules/channelmixerrgb/safety");
  dt_bauhaus_slider_set(g->safety, g->safety_margin);
 
  dt_iop_gui_leave_critical_section(self);
 
  // always disable profiling mode by default
  g->is_profiling_started = FALSE;
 
  dt_gui_hide_collapsible_section(&g->cs);
  dt_gui_update_collapsible_section(&g->csspot);
 
  g->spot_RGB[0] = 0.f;
  g->spot_RGB[1] = 0.f;
  g->spot_RGB[2] = 0.f;
  g->spot_RGB[3] = 0.f;
 
  // Widget defaults (reset values) and the image-dependent "as shot in camera" illuminant entry,
  // derived from the per-image defaults that reload_defaults() already computed into default_params.
  // This lives here, not in reload_defaults(), so it only touches widgets when they exist and on the
  // GUI thread (reload_defaults also runs on export/thumbnail devs that have no widgets).
  {
    const dt_iop_channelmixer_rgb_params_t *d = (const dt_iop_channelmixer_rgb_params_t *)self->default_params;
    const dt_image_t *img = &self->dev->image_storage;
    const dt_aligned_pixel_t xyY = { d->x, d->y, 1.f };
    dt_aligned_pixel_t Lch = { 0 };
    dt_xyY_to_Lch(xyY, Lch);
 
    dt_bauhaus_slider_set_default(g->illum_x, Lch[2] / M_PI * 180.f);
    dt_bauhaus_slider_set_default(g->illum_y, Lch[1]);
    dt_bauhaus_slider_set_default(g->temperature, d->temperature);
    dt_bauhaus_combobox_set_default(g->illuminant, d->illuminant);
    dt_bauhaus_combobox_set_default(g->adaptation, d->adaptation);
    if(g->delta_E_label_text)
    {
      dt_free(g->delta_E_label_text);
      g->delta_E_label_text = NULL;
    }
 
    if(dt_image_is_matrix_correction_supported(img) && !dt_image_is_monochrome(img))
    {
      if(dt_bauhaus_combobox_length(g->illuminant) < DT_ILLUMINANT_CAMERA + 1)
        dt_bauhaus_combobox_add_full(g->illuminant, _("as shot in camera"), DT_BAUHAUS_COMBOBOX_ALIGN_RIGHT,
                                     GINT_TO_POINTER(DT_ILLUMINANT_CAMERA), NULL, TRUE);
    }
    else
      dt_bauhaus_combobox_remove_at(g->illuminant, DT_ILLUMINANT_CAMERA);
  }
 
  dt_gui_freeze_end();
 
  gui_changed(self, NULL, NULL);
}
 
void init(dt_iop_module_t *module)
{
  dt_iop_default_init(module);
 
  dt_iop_channelmixer_rgb_params_t *d = (dt_iop_channelmixer_rgb_params_t *)module->default_params;
  d->red[0] = d->green[1] = d->blue[2] = 1.0;
  d->normalize_R = TRUE;
  d->normalize_G = TRUE;
  d->normalize_B = TRUE;
}
 
void reload_defaults(dt_iop_module_t *module)
{
  dt_iop_channelmixer_rgb_params_t *d = (dt_iop_channelmixer_rgb_params_t *)module->default_params;
 
  // Our per-image defaults (illuminant chromaticity x/y, temperature) are derived from the white
  // balance temperature publishes into dev->proxy.wb_coeffs (see get_white_balance_coeff()).
  // temperature publishes the per-image DEFAULT WB from its own reload_defaults() (main thread, no
  // pipeline involved). For that seed to be visible here, temperature must run before us:
  // dt_dev_init_default_history() iterates modules in iop order, and temperature's iop_order is far
  // below ours, so this holds -- but it is a silent data dependency, so assert it. A future
  // iop-order change that put us first would otherwise regress our defaults on a brand-new history.
  // (The EFFECTIVE/history WB is published later via temperature's commit_proxy(); our defaults are
  // intentionally keyed on the metadata-default WB so a fresh init always matches a manual reset.)
  const dt_iop_module_t *const temp = dt_iop_get_module_from_list(module->dev->iop, "temperature");
  if(temp && temp->iop_order >= module->iop_order)
    fprintf(stderr, "[channelmixerrgb] BUG: temperature (iop_order %d) must run before channelmixerrgb "
                    "(iop_order %d); white-balance-derived defaults will be wrong on a fresh history\n",
            temp->iop_order, module->iop_order);
  assert(!temp || temp->iop_order < module->iop_order);
 
  d->normalize_R = TRUE;
  d->normalize_G = TRUE;
  d->normalize_B = TRUE;
 
  d->x = module->get_f("x")->Float.Default;
  d->y = module->get_f("y")->Float.Default;
  d->temperature = module->get_f("temperature")->Float.Default;
  d->illuminant = module->get_f("illuminant")->Enum.Default;
  d->adaptation = module->get_f("adaptation")->Enum.Default;
 
  // Note : this is not an user param anymore, and is set to modern by default
  // except for old histories using temperature without having an history entry for it.
  // see develop/develop.c/_dev_auto_apply_presets()
  const gboolean is_modern =
    dt_conf_is_equal("plugins/darkroom/chromatic-adaptation", "modern");
 
  // note that if there is already an instance of this module with an
  // adaptation set we default to RGB (none) in this instance.
  // try to register the CAT here
  declare_cat_on_pipe(module, is_modern);
  const dt_image_t *img = &module->dev->image_storage;
 
  // check if we could register
  gboolean CAT_already_applied =
    (!IS_NULL_PTR(module->dev->proxy.chroma_adaptation))      // CAT exists
    && (module->dev->proxy.chroma_adaptation != module) // and it is not us
    && (!dt_image_is_monochrome(img));
 
  module->default_enabled = FALSE;
 
  dt_aligned_pixel_t custom_wb = { 1.f, 1.f, 1.f, 1.f };
  if(!CAT_already_applied
     && is_modern
     && !get_white_balance_coeff(module, custom_wb)
     && !dt_image_is_monochrome(img))
  {
    // if workflow = modern and we find WB coeffs, take care of white balance here
    if(find_temperature_from_raw_coeffs(img, custom_wb, &(d->x), &(d->y)))
      d->illuminant = DT_ILLUMINANT_CAMERA;
 
    check_if_close_to_daylight(d->x, d->y, &(d->temperature), &(d->illuminant), &(d->adaptation));
    module->workflow_enabled = dt_image_needs_rawprepare(img);
  }
  else
  {
    // otherwise, simple channel mixer
    d->illuminant = DT_ILLUMINANT_PIPE;
    d->adaptation = DT_ADAPTATION_RGB;
  }
 
  // NOTE: widget state (slider/combo defaults, the image-dependent "as shot in camera" illuminant
  // entry) is intentionally NOT set here. reload_defaults() runs on export/thumbnail devs with no
  // widgets and off the GUI thread; touching bauhaus here re-entered callbacks against half-built
  // widgets and crashed. That work now lives in gui_update(), reading these same default_params.
}
 
 
static void _spot_settings_changed_callback(GtkWidget *slider, dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_aligned_pixel_t Lch_target = { 0.f };
 
  dt_iop_gui_enter_critical_section(self);
  Lch_target[0] = dt_bauhaus_slider_get(g->lightness_spot);
  Lch_target[1] = dt_bauhaus_slider_get(g->chroma_spot);
  Lch_target[2] = dt_bauhaus_slider_get(g->hue_spot) / 360.f;
  const gboolean use_mixing = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(g->use_mixing));
  dt_iop_gui_leave_critical_section(self);
 
  // Save the color on change
  dt_conf_set_float("darkroom/modules/channelmixerrgb/lightness", Lch_target[0]);
  dt_conf_set_float("darkroom/modules/channelmixerrgb/chroma", Lch_target[1]);
  dt_conf_set_float("darkroom/modules/channelmixerrgb/hue", Lch_target[2] * 360.f);
  dt_conf_set_bool("darkroom/modules/channelmixerrgb/use_mixing", use_mixing);
 
  dt_gui_freeze_begin();
  paint_hue(self);
  dt_gui_freeze_end();
 
  // Re-run auto illuminant only for the module that currently owns the active picker.
  const dt_spot_mode_t mode = dt_bauhaus_combobox_get(g->spot_mode);
  const gboolean picker_active = dt_iop_color_picker_is_active_module(self);
  if(mode == DT_SPOT_MODE_CORRECT && picker_active)
    _auto_set_illuminant(self, self->dev->pipe);
  // else : just record new values and do nothing
}
 
static void _channelmixerrgb_set_mixer_mode(dt_iop_channelmixer_rgb_gui_data_t *const g,
                                            const dt_iop_channelmixer_rgb_mixer_mode_t mode)
{
  gtk_stack_set_visible_child_name(GTK_STACK(g->mixer_stack),
                                   mode == DT_CHANNELMIXERRGB_MIXER_SIMPLE ? "simple"
                                   : mode == DT_CHANNELMIXERRGB_MIXER_PRIMARIES ? "primaries"
                                   : mode == DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING ? "white-preserving"
                                   : "complete");
}
 
static gboolean _channelmixerrgb_push_matrix_to_params(dt_iop_module_t *self, const float M[3][3])
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  gboolean changed = p->normalize_R || p->normalize_G || p->normalize_B;
 
  for(int col = 0; col < 3; col++)
  {
    changed = changed || p->red[col] != M[0][col] || p->green[col] != M[1][col] || p->blue[col] != M[2][col];
    p->red[col] = M[0][col];
    p->green[col] = M[1][col];
    p->blue[col] = M[2][col];
  }
 
  p->normalize_R = FALSE;
  p->normalize_G = FALSE;
  p->normalize_B = FALSE;
 
  dt_gui_freeze_begin();
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_R), FALSE);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_G), FALSE);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_B), FALSE);
  dt_bauhaus_slider_set(g->scale_red_R, p->red[0]);
  dt_bauhaus_slider_set(g->scale_red_G, p->red[1]);
  dt_bauhaus_slider_set(g->scale_red_B, p->red[2]);
  dt_bauhaus_slider_set(g->scale_green_R, p->green[0]);
  dt_bauhaus_slider_set(g->scale_green_G, p->green[1]);
  dt_bauhaus_slider_set(g->scale_green_B, p->green[2]);
  dt_bauhaus_slider_set(g->scale_blue_R, p->blue[0]);
  dt_bauhaus_slider_set(g->scale_blue_G, p->blue[1]);
  dt_bauhaus_slider_set(g->scale_blue_B, p->blue[2]);
  dt_gui_freeze_end();
 
  return changed;
}
 
static void _channelmixerrgb_reject_mixer_mode(dt_iop_module_t *self, const char *message)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
 
  dt_control_log("%s", message);
  dt_gui_freeze_begin();
  dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
  dt_gui_freeze_end();
  _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
  dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
}
 
static void _channelmixerrgb_mixer_mode_callback(GtkWidget *combo, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const dt_iop_channelmixer_rgb_mixer_mode_t mode = dt_bauhaus_combobox_get(combo);
 
  dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, mode);
 
  if(mode == DT_CHANNELMIXERRGB_MIXER_COMPLETE)
  {
    _channelmixerrgb_set_mixer_mode(g, mode);
    return;
  }
 
  if(mode == DT_CHANNELMIXERRGB_MIXER_SIMPLE)
  {
    float error = INFINITY;
    if(!_channelmixerrgb_sync_simple_from_params(self, &error))
    {
      dt_control_log(_("simple mixer mode requires all three output rows to be normalized with non-zero sums."));
      dt_gui_freeze_begin();
      dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      dt_gui_freeze_end();
      _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      return;
    }
 
    _channelmixerrgb_set_mixer_mode(g, mode);
    gui_changed(self, NULL, NULL);
    return;
  }
 
  if(mode == DT_CHANNELMIXERRGB_MIXER_PRIMARIES)
  {
    const float rows[3][3] = { { p->red[0], p->red[1], p->red[2] },
                               { p->green[0], p->green[1], p->green[2] },
                               { p->blue[0], p->blue[1], p->blue[2] } };
    const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
    float M[3][3] = { { 0.f } };
    float error = INFINITY;
    if(!dt_iop_channelmixer_shared_get_matrix(rows, normalize, FALSE, M)
       || !_channelmixerrgb_sync_primaries_from_params(self, &error))
    {
      dt_control_log(_("primaries mixer mode requires a non-singular 3x3 matrix with non-zero affine sums."));
      dt_gui_freeze_begin();
      dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      dt_gui_freeze_end();
      _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      return;
    }
 
    gboolean changed = p->normalize_R || p->normalize_G || p->normalize_B;
    for(int col = 0; col < 3; col++)
    {
      changed = changed || p->red[col] != M[0][col] || p->green[col] != M[1][col] || p->blue[col] != M[2][col];
      p->red[col] = M[0][col];
      p->green[col] = M[1][col];
      p->blue[col] = M[2][col];
    }
 
    p->normalize_R = FALSE;
    p->normalize_G = FALSE;
    p->normalize_B = FALSE;
 
    dt_gui_freeze_begin();
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_R), FALSE);
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_G), FALSE);
    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_B), FALSE);
    dt_bauhaus_slider_set(g->scale_red_R, p->red[0]);
    dt_bauhaus_slider_set(g->scale_red_G, p->red[1]);
    dt_bauhaus_slider_set(g->scale_red_B, p->red[2]);
    dt_bauhaus_slider_set(g->scale_green_R, p->green[0]);
    dt_bauhaus_slider_set(g->scale_green_G, p->green[1]);
    dt_bauhaus_slider_set(g->scale_green_B, p->green[2]);
    dt_bauhaus_slider_set(g->scale_blue_R, p->blue[0]);
    dt_bauhaus_slider_set(g->scale_blue_G, p->blue[1]);
    dt_bauhaus_slider_set(g->scale_blue_B, p->blue[2]);
    dt_gui_freeze_end();
 
    _channelmixerrgb_set_mixer_mode(g, mode);
    gui_changed(self, NULL, NULL);
 
    if(changed)
    {
      dt_print(DT_DEBUG_DEV, "[channelmixerrgb] history commit source=mixer_mode_primaries\n");
      dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
    }
  }
 
  if(mode == DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING)
  {
    const float rows[3][3] = { { p->red[0], p->red[1], p->red[2] },
                               { p->green[0], p->green[1], p->green[2] },
                               { p->blue[0], p->blue[1], p->blue[2] } };
    const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
    float M[3][3] = { { 0.f } };
    float error = INFINITY;
    if(!dt_iop_channelmixer_shared_get_matrix(rows, normalize, FALSE, M)
       || !_channelmixerrgb_sync_white_preserving_from_params(self, &error))
    {
      _channelmixerrgb_reject_mixer_mode(
          self, _("white-preserving mixer mode requires a matrix that leaves the basis white unchanged."));
      return;
    }
 
    const gboolean changed = _channelmixerrgb_push_matrix_to_params(self, M);
 
    _channelmixerrgb_set_mixer_mode(g, mode);
    gui_changed(self, NULL, NULL);
 
    if(changed)
    {
      dt_print(DT_DEBUG_DEV, "[channelmixerrgb] history commit source=mixer_mode_white_preserving\n");
      dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
    }
  }
}
 
static void _channelmixerrgb_simple_slider_callback(GtkWidget *slider, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *const widgets[6]
      = { g->simple_theta, g->simple_psi, g->simple_stretch_1, g->simple_stretch_2, g->simple_coupling_1,
          g->simple_coupling_2 };
  dt_iop_channelmixer_rgb_simple_params_t simple;
  float M[3][3] = { { 0.f } };
 
  dt_iop_channelmixer_shared_simple_from_sliders(widgets, &simple);
  dt_iop_channelmixer_shared_simple_to_matrix(&simple, M);
 
  for(int col = 0; col < 3; col++)
  {
    p->red[col] = M[0][col];
    p->green[col] = M[1][col];
    p->blue[col] = M[2][col];
  }
 
  dt_gui_freeze_begin();
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_R), p->normalize_R);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_G), p->normalize_G);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_B), p->normalize_B);
 
  dt_bauhaus_slider_set(g->scale_red_R, p->red[0]);
  dt_bauhaus_slider_set(g->scale_red_G, p->red[1]);
  dt_bauhaus_slider_set(g->scale_red_B, p->red[2]);
  dt_bauhaus_slider_set(g->scale_green_R, p->green[0]);
  dt_bauhaus_slider_set(g->scale_green_G, p->green[1]);
  dt_bauhaus_slider_set(g->scale_green_B, p->green[2]);
  dt_bauhaus_slider_set(g->scale_blue_R, p->blue[0]);
  dt_bauhaus_slider_set(g->scale_blue_G, p->blue[1]);
  dt_bauhaus_slider_set(g->scale_blue_B, p->blue[2]);
  dt_gui_freeze_end();
 
  gui_changed(self, slider, NULL);
 
  dt_print(DT_DEBUG_DEV, "[channelmixerrgb] history commit source=simple_slider slider=%p\n", (void *)slider);
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void _channelmixerrgb_primaries_slider_callback(GtkWidget *slider, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *const widgets[9]
      = { g->primaries_achromatic_hue, g->primaries_achromatic_purity, g->primaries_red_hue,
          g->primaries_red_purity, g->primaries_green_hue, g->primaries_green_purity,
          g->primaries_blue_hue, g->primaries_blue_purity, g->primaries_gain };
  dt_iop_channelmixer_rgb_primaries_params_t primaries;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
  float M[3][3] = { { 0.f } };
 
  dt_iop_channelmixer_shared_primaries_from_sliders(widgets, &primaries);
  if(!dt_iop_channelmixer_shared_primaries_to_matrix(basis, &primaries, M))
  {
    dt_control_log(_("primaries mixer mode requires a non-singular 3x3 matrix with non-zero affine sums."));
    return;
  }
 
  for(int col = 0; col < 3; col++)
  {
    p->red[col] = M[0][col];
    p->green[col] = M[1][col];
    p->blue[col] = M[2][col];
  }
  p->normalize_R = FALSE;
  p->normalize_G = FALSE;
  p->normalize_B = FALSE;
 
  dt_gui_freeze_begin();
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_R), FALSE);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_G), FALSE);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(g->normalize_B), FALSE);
 
  dt_bauhaus_slider_set(g->scale_red_R, p->red[0]);
  dt_bauhaus_slider_set(g->scale_red_G, p->red[1]);
  dt_bauhaus_slider_set(g->scale_red_B, p->red[2]);
  dt_bauhaus_slider_set(g->scale_green_R, p->green[0]);
  dt_bauhaus_slider_set(g->scale_green_G, p->green[1]);
  dt_bauhaus_slider_set(g->scale_green_B, p->green[2]);
  dt_bauhaus_slider_set(g->scale_blue_R, p->blue[0]);
  dt_bauhaus_slider_set(g->scale_blue_G, p->blue[1]);
  dt_bauhaus_slider_set(g->scale_blue_B, p->blue[2]);
  dt_gui_freeze_end();
 
  gui_changed(self, slider, NULL);
 
  dt_print(DT_DEBUG_DEV, "[channelmixerrgb] history commit source=primaries_slider slider=%p\n", (void *)slider);
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
 
static void _channelmixerrgb_white_preserving_slider_callback(GtkWidget *slider, gpointer user_data)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  GtkWidget *widgets[6] = { NULL };
  dt_iop_channelmixer_rgb_white_preserving_params_t white_preserving;
  const dt_iop_channelmixer_rgb_primaries_basis_t basis
      = dt_iop_channelmixer_shared_primaries_basis_from_adaptation(p->adaptation);
  float M[3][3] = { { 0.f } };
 
  if(!_channelmixerrgb_white_preserving_widgets(g, widgets)) return;
 
  dt_iop_channelmixer_shared_white_preserving_from_sliders(widgets, &white_preserving);
  if(!dt_iop_channelmixer_shared_white_preserving_to_matrix(basis, &white_preserving, M))
  {
    // Three primaries collapsed onto the white have no transform to describe. Snap the sliders
    // back to the last representable state rather than leaving the page showing a setting the
    // params do not hold -- the render would otherwise stop following the controls.
    dt_control_log(_("white-preserving mixer mode requires non-degenerate primaries."));
    _channelmixerrgb_sync_white_preserving_from_params(self, NULL);
    return;
  }
 
  _channelmixerrgb_push_matrix_to_params(self, M);
 
  gui_changed(self, slider, NULL);
 
  dt_print(DT_DEBUG_DEV, "[channelmixerrgb] history commit source=white_preserving_slider slider=%p\n",
           (void *)slider);
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
 
void gui_changed(dt_iop_module_t *self, GtkWidget *w, void *previous)
{
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  const gboolean simple_widget
      = w == g->simple_theta || w == g->simple_psi || w == g->simple_stretch_1 || w == g->simple_stretch_2
        || w == g->simple_coupling_1 || w == g->simple_coupling_2;
  const gboolean primaries_widget
      = w == g->primaries_achromatic_hue || w == g->primaries_achromatic_purity || w == g->primaries_red_hue
        || w == g->primaries_red_purity || w == g->primaries_green_hue || w == g->primaries_green_purity
        || w == g->primaries_blue_hue || w == g->primaries_blue_purity || w == g->primaries_gain;
  const gboolean white_preserving_widget
      = w == g->white_preserving_red_rotation || w == g->white_preserving_red_saturation
        || w == g->white_preserving_green_rotation || w == g->white_preserving_green_saturation
        || w == g->white_preserving_blue_rotation || w == g->white_preserving_blue_saturation;
  GtkWidget *white_preserving_widgets[6] = { NULL };
  // Bauhaus setters emit gui_changed() from gui_init(), before this page has been built.
  const gboolean white_preserving_ready = _channelmixerrgb_white_preserving_widgets(g, white_preserving_widgets);
  const gboolean normalize[3] = { p->normalize_R, p->normalize_G, p->normalize_B };
  const gboolean rows_are_normalized = dt_iop_channelmixer_shared_rows_are_normalized(normalize);
  const gboolean complete_widget
      = w == g->scale_red_R || w == g->scale_red_G || w == g->scale_red_B || w == g->scale_green_R
        || w == g->scale_green_G || w == g->scale_green_B || w == g->scale_blue_R || w == g->scale_blue_G
        || w == g->scale_blue_B || w == g->normalize_R || w == g->normalize_G || w == g->normalize_B;
  // Some Bauhaus setters emit during gui_init(), so synchronize the illuminant group only after
  // every widget sharing the same xyY/Lch state has been created.
  const gboolean illuminant_widgets_ready
      = !IS_NULL_PTR(g->illuminant) && !IS_NULL_PTR(g->illum_fluo) && !IS_NULL_PTR(g->illum_led)
        && !IS_NULL_PTR(g->temperature) && !IS_NULL_PTR(g->illum_color) && !IS_NULL_PTR(g->illum_x)
        && !IS_NULL_PTR(g->illum_y);
 
  if(!IS_NULL_PTR(w) && w == g->illuminant)
  {
    if(!IS_NULL_PTR(previous))
    {
      dt_illuminant_t *prev_illuminant = (dt_illuminant_t *)previous;
      if(*prev_illuminant == DT_ILLUMINANT_CAMERA)
      {
        // If illuminant was previously set with "as set in camera",
        // when changing it, we need to ensure the temperature and chromaticity
        // are inited with the correct values taken from camera EXIF.
        // Otherwise, if using a preset defining illuminant = "as set in camera",
        // temperature and chromaticity are inited with the preset content when illuminant is changed.
        dt_aligned_pixel_t custom_wb;
        get_white_balance_coeff(self, custom_wb);
        find_temperature_from_raw_coeffs(&(self->dev->image_storage), custom_wb, &(p->x), &(p->y));
        check_if_close_to_daylight(p->x, p->y, &(p->temperature), NULL, &(p->adaptation));
      }
    }
    if(p->illuminant == DT_ILLUMINANT_CAMERA)
    {
      // Get camera WB and update illuminant
      dt_aligned_pixel_t custom_wb;
      get_white_balance_coeff(self, custom_wb);
      const int found = find_temperature_from_raw_coeffs(&(self->dev->image_storage), custom_wb, &(p->x), &(p->y));
      check_if_close_to_daylight(p->x, p->y, &(p->temperature), NULL, &(p->adaptation));
 
      if(found)
        dt_control_log(_("white balance successfully extracted from raw image"));
    }
    else if(p->illuminant == DT_ILLUMINANT_DETECT_EDGES
            || p->illuminant == DT_ILLUMINANT_DETECT_SURFACES)
    {
      // We need to recompute only the full preview
      dt_control_log(_("auto-detection of white balance started..."));
    }
  }
 
  if(!IS_NULL_PTR(w) && (w == g->illuminant || w == g->illum_fluo || w == g->illum_led || w == g->temperature))
  {
    // Convert and synchronize all the possible ways to define an illuminant to allow swapping modes
 
    if(p->illuminant != DT_ILLUMINANT_CUSTOM && p->illuminant != DT_ILLUMINANT_CAMERA)
    {
      // We are in any mode defining (x, y) indirectly from an interface, so commit (x, y) explicitly
      illuminant_to_xy(p->illuminant, NULL, NULL, &(p->x), &(p->y), p->temperature, p->illum_fluo, p->illum_led);
    }
 
    if(p->illuminant != DT_ILLUMINANT_D && p->illuminant != DT_ILLUMINANT_BB && p->illuminant != DT_ILLUMINANT_CAMERA)
    {
      // We are in any mode not defining explicitly a temperature, so find the the closest CCT and commit it
      check_if_close_to_daylight(p->x, p->y, &(p->temperature), NULL, NULL);
    }
  }
 
  dt_gui_freeze_begin();
 
  if(IS_NULL_PTR(w) || w == g->hue_spot || w == g->chroma_spot || w == g->lightness_spot || w == g->spot_settings)
  {
    paint_hue(self);
  }
 
  if((IS_NULL_PTR(w) || w == g->illuminant || w == g->illum_fluo || w == g->illum_led || w == g->temperature)
     && illuminant_widgets_ready)
  {
    update_illuminants(self);
    update_approx_cct(self);
    update_illuminant_color(self);
 
    // force-update all the illuminant sliders in case something above changed them
    // notice the hue/chroma of the illuminant has to be computed on-the-fly anyway
    dt_aligned_pixel_t xyY = { p->x, p->y, 1.f };
    dt_aligned_pixel_t Lch;
    dt_xyY_to_Lch(xyY, Lch);
 
    // If the chroma is zero then there is not a meaningful hue angle. In this case
    // leave the hue slider where it was, so that if chroma is set to zero and then
    // set to a nonzero value, the hue setting will remain unchanged.
    if(Lch[1] > 0)
      dt_bauhaus_slider_set(g->illum_x, Lch[2] / M_PI * 180.f);
    dt_bauhaus_slider_set(g->illum_y, Lch[1]);
 
    // Redraw the temperature background color taking new soft bounds into account
    dt_bauhaus_slider_set(g->temperature, p->temperature);
    dt_iop_channelmixer_shared_paint_temperature_slider(g->temperature, TEMP_MIN, TEMP_MAX);
  }
 
  if(w == g->adaptation)
    update_illuminants(self);
 
  if(IS_NULL_PTR(w) || w == g->adaptation || primaries_widget || white_preserving_widget || w == g->scale_red_R   || w == g->scale_red_G   || w == g->scale_red_B   || w == g->normalize_R)
    _update_RGB_colors(self, 1, 0, 0, p->normalize_R, p->red, g->scale_red_R, g->scale_red_G, g->scale_red_B);
  if(IS_NULL_PTR(w) || w == g->adaptation || primaries_widget || white_preserving_widget || w == g->scale_green_R || w == g->scale_green_G || w == g->scale_green_B || w == g->normalize_G)
    _update_RGB_colors(self, 0, 1, 0, p->normalize_G, p->green, g->scale_green_R, g->scale_green_G, g->scale_green_B);
  if(IS_NULL_PTR(w) || w == g->adaptation || primaries_widget || white_preserving_widget || w == g->scale_blue_R  || w == g->scale_blue_G  || w == g->scale_blue_B  || w == g->normalize_B)
    _update_RGB_colors(self, 0, 0, 1, p->normalize_B, p->blue, g->scale_blue_R, g->scale_blue_G, g->scale_blue_B);
 
  if(rows_are_normalized && !simple_widget && (IS_NULL_PTR(w) || complete_widget))
  {
    float error = INFINITY;
    if(!_channelmixerrgb_sync_simple_from_params(self, &error))
    {
      if(dt_bauhaus_combobox_get(g->mixer_mode) == DT_CHANNELMIXERRGB_MIXER_SIMPLE)
      {
        dt_print(DT_DEBUG_DEV, "[channelmixerrgb] simple mixer rejected error=%g normalized=%d%d%d\n",
                 error, p->normalize_R, p->normalize_G, p->normalize_B);
        dt_control_log(_("simple mixer mode requires all three output rows to be normalized with non-zero sums."));
        dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      }
      else
        dt_print(DT_DEBUG_DEV, "[channelmixerrgb] simple mixer roundtrip error=%g\n", error);
    }
  }
 
  if(!primaries_widget && (IS_NULL_PTR(w) || complete_widget || simple_widget || w == g->adaptation))
  {
    float error = INFINITY;
    if(!_channelmixerrgb_sync_primaries_from_params(self, &error))
    {
      if(dt_bauhaus_combobox_get(g->mixer_mode) == DT_CHANNELMIXERRGB_MIXER_PRIMARIES)
      {
        dt_print(DT_DEBUG_DEV, "[channelmixerrgb] primaries mixer roundtrip error=%g\n", error);
        dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      }
    }
  }
 
  if(white_preserving_ready && !white_preserving_widget
     && (IS_NULL_PTR(w) || complete_widget || simple_widget || primaries_widget || w == g->adaptation))
  {
    float error = INFINITY;
    if(!_channelmixerrgb_sync_white_preserving_from_params(self, &error))
    {
      if(dt_bauhaus_combobox_get(g->mixer_mode) == DT_CHANNELMIXERRGB_MIXER_WHITE_PRESERVING)
      {
        dt_print(DT_DEBUG_DEV, "[channelmixerrgb] white-preserving mixer roundtrip error=%g\n", error);
        dt_conf_set_int(DT_CHANNELMIXERRGB_SIMPLE_MODE_CONF, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        dt_bauhaus_combobox_set(g->mixer_mode, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
        _channelmixerrgb_set_mixer_mode(g, DT_CHANNELMIXERRGB_MIXER_COMPLETE);
      }
    }
  }
 
  if(IS_NULL_PTR(w) || w == g->adaptation || complete_widget || simple_widget || primaries_widget
     || white_preserving_widget)
    _channelmixerrgb_update_simple_colors(self);
 
  if(IS_NULL_PTR(w) || w == g->adaptation || complete_widget || simple_widget || primaries_widget
     || white_preserving_widget)
    _channelmixerrgb_update_primaries_colors(self);
 
  if(IS_NULL_PTR(w) || w == g->adaptation || complete_widget || simple_widget || primaries_widget
     || white_preserving_widget)
    _channelmixerrgb_update_white_preserving_colors(self);
 
  // if grey channel is used and norm = 0 and normalization = ON, we are going to have a division by zero
  // in commit_param, we avoid dividing by zero automatically, but user needs a notification
  if((p->grey[0] != 0.f) || (p->grey[1] != 0.f) || (p->grey[2] != 0.f))
    if((p->grey[0] + p->grey[1] + p->grey[2] == 0.f) && p->normalize_grey)
      dt_control_log(_("color calibration: the sum of the gray channel parameters is zero, normalization will be disabled."));
 
  // If "as shot in camera" illuminant is used, CAT space is forced automatically
  // therefore, make the control insensitive
  gtk_widget_set_sensitive(g->adaptation, p->illuminant != DT_ILLUMINANT_CAMERA);
  gtk_widget_queue_draw(g->adaptation);
 
  declare_cat_on_pipe(self, FALSE);
 
  dt_gui_freeze_end();
}
 
void _auto_set_illuminant(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  const dt_iop_channelmixer_rgb_params_t previous = *p;
 
  // capture gui color picked event.
  if(self->picked_color_max[0] < self->picked_color_min[0])
  {
    dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] rejected invalid min/max min=%g max=%g\n",
             self->picked_color_min[0], self->picked_color_max[0]);
    return;
  }
  const float *RGB = self->picked_color;
  if(!isfinite(RGB[0]) || !isfinite(RGB[1]) || !isfinite(RGB[2]))
  {
    dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] rejected nonfinite RGB=(%g,%g,%g)\n",
             RGB[0], RGB[1], RGB[2]);
    return;
  }
  dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] RGB=(%g,%g,%g) pipe=%p\n",
           RGB[0], RGB[1], RGB[2], (void *)pipe);
 
  // Get the module-stage profile matching the sampled buffer.
  const dt_iop_order_iccprofile_info_t *const current_profile
      = dt_ioppr_get_pipe_current_profile_info(self, pipe);
  if(IS_NULL_PTR(current_profile))
  {
    dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] missing current profile\n");
    return;
  }
 
  // Convert the sampled linear RGB code values to XYZ in the module profile.
  // The picker already sampled the live module buffer, so keep the conversion explicit here.
  dt_aligned_pixel_t XYZ = { 0.f };
  dot_product(RGB, current_profile->matrix_in, XYZ);
  if(!isfinite(XYZ[0]) || !isfinite(XYZ[1]) || !isfinite(XYZ[2])) return;
  dt_XYZ_to_sRGB(XYZ, g->spot_RGB);
 
  // Convert to Lch for GUI feedback (input)
  dt_aligned_pixel_t Lab;
  dt_aligned_pixel_t Lch;
  dt_XYZ_to_Lab(XYZ, Lab);
  dt_Lab_2_LCH(Lab, Lch);
 
  // Write report in GUI
  dt_gui_freeze_begin();
  gtk_label_set_text(GTK_LABEL(g->Lch_origin),
                     g_strdup_printf(_("L: \t%.1f %%\nh: \t%.1f \302\260\nc: \t%.1f"),
                                     Lch[0], Lch[2] * 360.f, Lch[1] ));
  gtk_widget_queue_draw(g->origin_spot);
  dt_gui_freeze_end();
 
  const dt_spot_mode_t mode = dt_bauhaus_combobox_get(g->spot_mode);
  const gboolean use_mixing = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(g->use_mixing));
 
  // build the channel mixing matrix - keep in synch with commit_params()
  dt_colormatrix_t MIX = { { 0.f } };
 
  float norm_R = 1.0f;
  if(p->normalize_R) norm_R = p->red[0] + p->red[1] + p->red[2];
 
  float norm_G = 1.0f;
  if(p->normalize_G) norm_G = p->green[0] + p->green[1] + p->green[2];
 
  float norm_B = 1.0f;
  if(p->normalize_B) norm_B = p->blue[0] + p->blue[1] + p->blue[2];
 
  for(int i = 0; i < 3; i++)
  {
    MIX[0][i] = p->red[i] / norm_R;
    MIX[1][i] = p->green[i] / norm_G;
    MIX[2][i] = p->blue[i] / norm_B;
  }
 
  if(mode == DT_SPOT_MODE_MEASURE)
  {
    // Keep the following in sync with commit_params()
 
    // find x y coordinates of illuminant for CIE 1931 2° observer
    float x = p->x;
    float y = p->y;
    dt_adaptation_t adaptation = p->adaptation;
    dt_aligned_pixel_t custom_wb;
    get_white_balance_coeff(self, custom_wb);
    illuminant_to_xy(p->illuminant, &(self->dev->image_storage), custom_wb, &x, &y, p->temperature, p->illum_fluo, p->illum_led);
 
    // if illuminant is set as camera, x and y are set on-the-fly at commit time, so we need to set adaptation too
    if(p->illuminant == DT_ILLUMINANT_CAMERA) check_if_close_to_daylight(x, y, NULL, NULL, &adaptation);
 
    // Convert illuminant from xyY to XYZ
    dt_aligned_pixel_t XYZ_illuminant = { 0.f };
    illuminant_xy_to_XYZ(x, y, XYZ_illuminant);
 
    // Convert illuminant from XYZ to Bradford modified LMS
    dt_aligned_pixel_t LMS_illuminant = { 0.f };
    dt_store_simd_aligned(LMS_illuminant, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_illuminant), adaptation));
 
    // For the non-linear Bradford
    const float pp = powf(0.818155f / LMS_illuminant[2], 0.0834f);
 
    //fprintf(stdout, "illuminant: %i\n", p->illuminant);
    //fprintf(stdout, "x: %f, y: %f\n", x, y);
    //fprintf(stdout, "X: %f - Y: %f - Z: %f\n", XYZ_illuminant[0], XYZ_illuminant[1], XYZ_illuminant[2]);
    //fprintf(stdout, "L: %f - M: %f - S: %f\n", LMS_illuminant[0], LMS_illuminant[1], LMS_illuminant[2]);
 
    // Finally, chroma-adapt the pixel
    dt_aligned_pixel_t XYZ_output = { 0.f };
    dt_store_simd_aligned(XYZ_output, chroma_adapt_pixel(dt_load_simd_aligned(XYZ),
                                                         dt_load_simd_aligned(LMS_illuminant),
                                                         adaptation, pp));
 
    // Optionaly, apply the channel mixing
    if(use_mixing)
    {
      dt_aligned_pixel_t LMS_output = { 0.f };
      dt_store_simd_aligned(LMS_output, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_output), adaptation));
      dt_aligned_pixel_t temp = { 0.f };
      dot_product(LMS_output, MIX, temp);
      dt_store_simd_aligned(XYZ_output, convert_any_LMS_to_XYZ(dt_load_simd_aligned(temp), adaptation));
    }
 
    // Convert to Lab and Lch for GUI feedback
    dt_aligned_pixel_t Lab_output = { 0.f };
    dt_aligned_pixel_t Lch_output = { 0.f };
    dt_XYZ_to_Lab(XYZ_output, Lab_output);
    dt_Lab_2_LCH(Lab_output, Lch_output);
 
    // Return the values in sliders
    dt_gui_freeze_begin();
    dt_bauhaus_slider_set(g->lightness_spot, Lch_output[0]);
    dt_bauhaus_slider_set(g->chroma_spot, Lch_output[1]);
    dt_bauhaus_slider_set(g->hue_spot, Lch_output[2] * 360.f);
    paint_hue(self);
    dt_gui_freeze_end();
 
    dt_conf_set_float("darkroom/modules/channelmixerrgb/lightness", Lch_output[0]);
    dt_conf_set_float("darkroom/modules/channelmixerrgb/chroma", Lch_output[1]);
    dt_conf_set_float("darkroom/modules/channelmixerrgb/hue", Lch_output[2] * 360.f);
    dt_conf_set_bool("darkroom/modules/channelmixerrgb/use_mixing", use_mixing);
  }
  else if(mode == DT_SPOT_MODE_CORRECT)
  {
    // Get the target color in LMS space
    dt_aligned_pixel_t Lch_target = { 0.f };
    dt_aligned_pixel_t Lab_target = { 0.f };
    dt_aligned_pixel_t XYZ_target = { 0.f };
    dt_aligned_pixel_t LMS_target = { 0.f };
 
    dt_iop_gui_enter_critical_section(self);
    Lch_target[0] = dt_bauhaus_slider_get(g->lightness_spot);
    Lch_target[1] = dt_bauhaus_slider_get(g->chroma_spot);
    Lch_target[2] = dt_bauhaus_slider_get(g->hue_spot) / 360.f;
    dt_iop_gui_leave_critical_section(self);
 
    dt_LCH_2_Lab(Lch_target, Lab_target);
    dt_Lab_to_XYZ(Lab_target, XYZ_target);
    const float Y_target = XYZ_target[1];
    for(int c = 0; c < 3; c++) XYZ_target[c] /= Y_target;
    dt_store_simd_aligned(LMS_target, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_target), p->adaptation));
 
    // optionaly, apply the inverse mixing on the target
    if(use_mixing)
    {
      // Repack the MIX matrix to 3x3 to support the pseudoinverse function
      // I'm just too lazy to rewrite the pseudo-inverse for 3x4 padded input
      float MIX_3x3[9];
      pack_3xSSE_to_3x3(MIX, MIX_3x3);
 
      /* DEBUG
      fprintf(stdout, "Repacked channel mixer matrix :\n");
      fprintf(stdout, "%f \t%f \t%f\n", MIX_3x3[0][0], MIX_3x3[0][1], MIX_3x3[0][2]);
      fprintf(stdout, "%f \t%f \t%f\n", MIX_3x3[1][0], MIX_3x3[1][1], MIX_3x3[1][2]);
      fprintf(stdout, "%f \t%f \t%f\n", MIX_3x3[2][0], MIX_3x3[2][1], MIX_3x3[2][2]);
      */
 
      // Invert the matrix
      float MIX_INV_3x3[9];
      matrice_pseudoinverse((float (*)[3])MIX_3x3, (float (*)[3])MIX_INV_3x3, 3);
 
      // Transpose and repack the inverse to SSE matrix because the inversion transposes too
      dt_colormatrix_t MIX_INV;
      transpose_3x3_to_3xSSE(MIX_INV_3x3, MIX_INV);
 
      /* DEBUG
      fprintf(stdout, "Repacked inverted channel mixer matrix :\n");
      fprintf(stdout, "%f \t%f \t%f\n", MIX_INV[0][0], MIX_INV[0][1], MIX_INV[0][2]);
      fprintf(stdout, "%f \t%f \t%f\n", MIX_INV[1][0], MIX_INV[1][1], MIX_INV[1][2]);
      fprintf(stdout, "%f \t%f \t%f\n", MIX_INV[2][0], MIX_INV[2][1], MIX_INV[2][2]);
      */
 
      // Undo the channel mixing on the reference color
      // So we get the expected target color after the CAT
      dt_aligned_pixel_t temp;
      dot_product(LMS_target, MIX_INV, temp);
 
      //fprintf(stdout, "LMS before channel mixer inversion : \t%f \t%f \t%f\n", LMS_target[0], LMS_target[1], LMS_target[2]);
      //fprintf(stdout, "LMS after channel mixer inversion : \t%f \t%f \t%f\n", temp[0], temp[1], temp[2]);
 
      // convert back to XYZ to normalize luminance again
      // in case the matrix is not normalized
      dt_store_simd_aligned(XYZ_target, convert_any_LMS_to_XYZ(dt_load_simd_aligned(temp), p->adaptation));
      const float Y_mix = XYZ_target[1];
      for(int c = 0; c < 3; c++) XYZ_target[c] /= Y_mix;
      dt_store_simd_aligned(LMS_target, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_target), p->adaptation));
 
      //fprintf(stdout, "LMS target after everything : %f \t%f \t%f\n", LMS_target[0], LMS_target[1], LMS_target[2]);
 
      // So now we got the target color after CAT and before mixing
      // in LMS space
    }
 
    // Get the input color in LMS space
    dt_aligned_pixel_t LMS = { 0.f };
    const float Y = XYZ[1];
    for(int c = 0; c < 3; c++) XYZ[c] /= Y;
    dt_store_simd_aligned(LMS, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ), p->adaptation));
 
    // Find the illuminant
    dt_aligned_pixel_t D50;
    convert_D50_to_LMS(p->adaptation, D50);
 
    dt_aligned_pixel_t illuminant_LMS = { 0.f };
    dt_aligned_pixel_t illuminant_XYZ = { 0.f };
 
    // We solve the equation : target color / input color = D50 / illuminant, for illuminant
    for(int c = 0; c < 3; c++) illuminant_LMS[c] = D50[c] * LMS[c] / LMS_target[c];
    dt_store_simd_aligned(illuminant_XYZ, convert_any_LMS_to_XYZ(dt_load_simd_aligned(illuminant_LMS), p->adaptation));
 
    // Convert to xyY
    const float sum = fmaxf(illuminant_XYZ[0] + illuminant_XYZ[1] + illuminant_XYZ[2], NORM_MIN);
    illuminant_XYZ[0] /= sum;              // x
    illuminant_XYZ[2] = illuminant_XYZ[1]; // Y
    illuminant_XYZ[1] /= sum;              // y
 
    p->x = illuminant_XYZ[0];
    p->y = illuminant_XYZ[1];
 
    // Force illuminant to custom, the daylight/black body approximations are
    // not accurate enough for color matching
    p->illuminant = DT_ILLUMINANT_CUSTOM;
 
    dt_gui_freeze_begin();
 
    check_if_close_to_daylight(p->x, p->y, &p->temperature, NULL, NULL);
 
    dt_bauhaus_slider_set(g->temperature, p->temperature);
    dt_bauhaus_combobox_set(g->illuminant, p->illuminant);
    dt_bauhaus_combobox_set(g->adaptation, p->adaptation);
 
    const dt_aligned_pixel_t xyY = { p->x, p->y, 1.f };
    dt_aligned_pixel_t Lch_illuminant = { 0 };
    dt_xyY_to_Lch(xyY, Lch_illuminant);
    dt_bauhaus_slider_set(g->illum_x, Lch_illuminant[2] / M_PI * 180.f);
    dt_bauhaus_slider_set(g->illum_y, Lch_illuminant[1]);
 
    update_illuminants(self);
    update_approx_cct(self);
    update_illuminant_color(self);
    paint_hue(self);
    dt_iop_channelmixer_shared_paint_temperature_slider(g->temperature, TEMP_MIN, TEMP_MAX);
    gtk_widget_queue_draw(g->origin_spot);
 
    dt_gui_freeze_end();
 
    if(memcmp(&previous, p, sizeof(previous)) != 0)
    {
      /* Auto-illuminant is driven by live picker motion, so this commits once per sampled
         move. That used to outpace the preview worker and keep it permanently in
         TOP_CHANGED, which is why this call was routed through a throttle of its own; the
         history commit now batches the resync it triggers, so the picker stays live without
         any special handling here. */
      dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] history commit source=auto_set_illuminant\n");
      dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
    }
  }
}
 
 
void color_picker_apply(dt_iop_module_t *self, GtkWidget *picker, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_print(DT_DEBUG_DEV, "[picker/channelmixerrgb] apply picker=%p pipe=%p\n", (void *)picker, (void *)pipe);
  _auto_set_illuminant(self, pipe);
}
 
 
void autoset(struct dt_iop_module_t *self, const struct dt_dev_pixelpipe_t *pipe,
             const struct dt_dev_pixelpipe_iop_t *piece, const void *i)
{
  const dt_iop_roi_t *const roi_out = &piece->roi_out;
  dt_iop_channelmixer_rgb_params_t *p = (dt_iop_channelmixer_rgb_params_t *)self->params;
  if(piece->dsc_in.channels != 4) return;
 
  const dt_iop_order_iccprofile_info_t *const current_profile
      = dt_ioppr_get_pipe_current_profile_info(self, pipe);
  if(IS_NULL_PTR(current_profile)) return;
 
  dt_colormatrix_t MIX = { { 0.f } };
 
  float norm_R = 1.0f;
  if(p->normalize_R) norm_R = p->red[0] + p->red[1] + p->red[2];
 
  float norm_G = 1.0f;
  if(p->normalize_G) norm_G = p->green[0] + p->green[1] + p->green[2];
 
  float norm_B = 1.0f;
  if(p->normalize_B) norm_B = p->blue[0] + p->blue[1] + p->blue[2];
 
  for(int c = 0; c < 3; c++)
  {
    MIX[0][c] = p->red[c] / norm_R;
    MIX[1][c] = p->green[c] / norm_G;
    MIX[2][c] = p->blue[c] / norm_B;
  }
 
  float lightness = 50.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/lightness"))
    lightness = dt_conf_get_float("darkroom/modules/channelmixerrgb/lightness");
 
  float hue = 0.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/hue"))
    hue = dt_conf_get_float("darkroom/modules/channelmixerrgb/hue");
 
  float chroma = 0.f;
  if(dt_conf_key_exists("darkroom/modules/channelmixerrgb/chroma"))
    chroma = dt_conf_get_float("darkroom/modules/channelmixerrgb/chroma");
 
  dt_aligned_pixel_t Lch_target = { lightness, chroma, hue / 360.f, 0.f };
  dt_aligned_pixel_t Lab_target = { 0.f };
  dt_aligned_pixel_t XYZ_target = { 0.f };
  dt_aligned_pixel_t LMS_target = { 0.f };
  dt_LCH_2_Lab(Lch_target, Lab_target);
  dt_Lab_to_XYZ(Lab_target, XYZ_target);
 
  // Normalize for unit luminance (illuminant)
  const float Y_target = XYZ_target[1];
  for(int c = 0; c < 3; c++) XYZ_target[c] /= Y_target;
  dt_store_simd_aligned(LMS_target, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_target), p->adaptation));
 
  float MIX_3x3[9];
  pack_3xSSE_to_3x3(MIX, MIX_3x3);
 
  float MIX_INV_3x3[9];
  matrice_pseudoinverse((float (*)[3])MIX_3x3, (float (*)[3])MIX_INV_3x3, 3);
 
  dt_colormatrix_t MIX_INV;
  transpose_3x3_to_3xSSE(MIX_INV_3x3, MIX_INV);
 
  dt_aligned_pixel_t temp = { 0.f };
  dot_product(LMS_target, MIX_INV, temp);
 
  dt_store_simd_aligned(XYZ_target, convert_any_LMS_to_XYZ(dt_load_simd_aligned(temp), p->adaptation));
  const float Y_mix = XYZ_target[1];
  if(Y_mix <= NORM_MIN) return;
  for(int c = 0; c < 3; c++) XYZ_target[c] /= Y_mix;
  dt_store_simd_aligned(LMS_target, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ_target), p->adaptation));
 
  const float *const restrict in = (float *)i;
  float average_L = 0.f;
  float average_M = 0.f;
  float average_S = 0.f;
  size_t valid_pixels = 0;
 
  // Compute average LMS in the image
  __OMP_PARALLEL_FOR__(reduction(+:average_L, average_M, average_S, valid_pixels))
  for(size_t k = 0; k < roi_out->width * roi_out->height * 4; k += 4)
  {
    // Convert each input pixel to the module CAT space first, then average the chromaticity there.
    dt_aligned_pixel_t XYZ = { 0.f };
    dt_aligned_pixel_t LMS = { 0.f };
    dt_ioppr_rgb_matrix_to_xyz(in + k, XYZ, current_profile->matrix_in_transposed, current_profile->lut_in,
                               current_profile->unbounded_coeffs_in, current_profile->lutsize,
                               current_profile->nonlinearlut);
 
    dt_store_simd_aligned(LMS, convert_any_XYZ_to_LMS(dt_load_simd_aligned(XYZ), p->adaptation));
    if(!isfinite(LMS[0]) || !isfinite(LMS[1]) || !isfinite(LMS[2])) continue;
 
    average_L += LMS[0];
    average_M += LMS[1];
    average_S += LMS[2];
    valid_pixels++;
  }
 
  if(valid_pixels == 0) return;
 
  const float norm = 1.f / (float)valid_pixels;
  dt_aligned_pixel_t average_LMS = { average_L * norm, average_M * norm, average_S * norm, 0.f };
 
  // Normalize for unit luminance
  dt_aligned_pixel_t average_XYZ = { 0.f };
  dt_store_simd_aligned(average_XYZ, convert_any_LMS_to_XYZ(dt_load_simd_aligned(average_LMS), p->adaptation));
  const float Y_average_lms = average_XYZ[1];
  for(int c = 0; c < 3; c++) average_XYZ[c] /= Y_average_lms;
  dt_store_simd_aligned(average_LMS, convert_any_XYZ_to_LMS(dt_load_simd_aligned(average_XYZ), p->adaptation));
 
  dt_aligned_pixel_t D50 = { 0.f };
  dt_aligned_pixel_t illuminant_LMS = { 0.f };
  dt_aligned_pixel_t illuminant_XYZ = { 0.f };
  convert_D50_to_LMS(p->adaptation, D50);
 
  for(int c = 0; c < 3; c++)
  {
    const float target = copysignf(fmaxf(fabsf(LMS_target[c]), NORM_MIN), LMS_target[c]);
    illuminant_LMS[c] = D50[c] * average_LMS[c] / target;
  }
 
  dt_store_simd_aligned(illuminant_XYZ, convert_any_LMS_to_XYZ(dt_load_simd_aligned(illuminant_LMS), p->adaptation));
 
  const float sum = fmaxf(illuminant_XYZ[0] + illuminant_XYZ[1] + illuminant_XYZ[2], NORM_MIN);
  p->x = illuminant_XYZ[0] / sum;
  p->y = illuminant_XYZ[1] / sum;
  p->illuminant = DT_ILLUMINANT_CUSTOM;
  check_if_close_to_daylight(p->x, p->y, &p->temperature, NULL, NULL);
}
 
 
void gui_init(struct dt_iop_module_t *self)
{
  dt_iop_channelmixer_rgb_gui_data_t *g = IOP_GUI_ALLOC(channelmixer_rgb);
 
  // Init the color checker UI
  for(size_t k = 0; k < 4; k++)
  {
    g->box[k].x = g->box[k].y = -1.;
    g->active_node[k] = FALSE;
  }
  g->is_cursor_close = FALSE;
  g->drag_drop = FALSE;
  g->is_profiling_started = FALSE;
  g->run_profile = FALSE;
  g->run_validation = FALSE;
  g->profile_ready = FALSE;
  g->checker_ready = FALSE;
  g->delta_E_in = NULL;
  g->delta_E_label_text = NULL;
  g->colorcheckers = NULL;
 
  g->XYZ[0] = NAN;
 
  DT_DEBUG_CONTROL_SIGNAL_CONNECT(dt_control_signal_get_global(), DT_SIGNAL_DEVELOP_UI_PIPE_FINISHED,
                            G_CALLBACK(_develop_ui_pipe_finished_callback), self);
  DT_DEBUG_CONTROL_SIGNAL_CONNECT(dt_control_signal_get_global(), DT_SIGNAL_DEVELOP_PREVIEW_PIPE_FINISHED,
                                  G_CALLBACK(_preview_pipe_finished_callback), self);
 
  // Init GTK notebook
  g->notebook = dt_ui_notebook_new();
  // The CAT page's illuminant picker is read at apply time; reset it if it is
  // still active once the user switches away from that page.
  dt_ui_notebook_set_picker_owner(g->notebook, self);
 
  // Page CAT
  self->gui->widget = dt_ui_notebook_page(g->notebook, N_("CAT"), _("chromatic adaptation transform"));
 
  g->adaptation = dt_bauhaus_combobox_from_params(self, N_("adaptation"));
  gtk_widget_set_tooltip_text(GTK_WIDGET(g->adaptation),
                              _("choose the method to adapt the illuminant\n"
                                "and the colorspace in which the module works: \n"
                                "- Linear Bradford (1985) is consistent with ICC v4 toolchain.\n"
                                "- CAT16 (2016) is more robust and accurate.\n"
                                "- Non-linear Bradford (1985) is the original Bradford,\n"
                                "  it can produce better results than the linear version, but is unreliable.\n"
                                "- XYZ is a simple scaling in XYZ space. It is not recommended in general.\n"
                                "- none disables any adaptation and uses pipeline working RGB."));
 
  GtkWidget *hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_GUI_BOX_SPACING);
 
  g->approx_cct = dt_ui_label_new("CCT:");
  gtk_box_pack_start(GTK_BOX(hbox), g->approx_cct, FALSE, FALSE, 0);
 
  g->illum_color = GTK_WIDGET(gtk_drawing_area_new());
  gtk_widget_set_size_request(g->illum_color, 2 * DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width),
                                              DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width));
  gtk_widget_set_tooltip_text(GTK_WIDGET(g->illum_color),
                              _("this is the color of the scene illuminant before chromatic adaptation\n"
                                "this color will be turned into pure white by the adaptation."));
 
  g_signal_connect(G_OBJECT(g->illum_color), "draw", G_CALLBACK(illuminant_color_draw), self);
  gtk_box_pack_start(GTK_BOX(hbox), g->illum_color, TRUE, TRUE, 0);
 
  g->color_picker = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, hbox);
  gtk_widget_set_tooltip_text(g->color_picker, _("set white balance to detected from area"));
 
  gtk_box_pack_start(GTK_BOX(self->gui->widget), GTK_WIDGET(hbox), FALSE, FALSE, 0);
 
  g->illuminant = dt_bauhaus_combobox_from_params(self, N_("illuminant"));
 
  g->illum_fluo = dt_bauhaus_combobox_from_params(self, "illum_fluo");
 
  g->illum_led = dt_bauhaus_combobox_from_params(self, "illum_led");
 
  g->temperature = dt_bauhaus_slider_from_params(self, N_("temperature"));
 
  g->illum_x = dt_bauhaus_slider_new_with_range_and_feedback(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., ILLUM_X_MAX, 0, 0, 1, 0);
  dt_bauhaus_widget_set_label(g->illum_x, N_("hue"));
  dt_bauhaus_slider_set_format(g->illum_x, "\302\260");
  g_signal_connect(G_OBJECT(g->illum_x), "value-changed", G_CALLBACK(illum_xy_callback), self);
  gtk_box_pack_start(GTK_BOX(self->gui->widget), GTK_WIDGET(g->illum_x), FALSE, FALSE, 0);
 
  g->illum_y = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., 100., 0, 0, 1);
  dt_bauhaus_widget_set_label(g->illum_y, N_("chroma"));
  dt_bauhaus_slider_set_format(g->illum_y, "%");
  dt_bauhaus_slider_set_hard_max(g->illum_y, ILLUM_Y_MAX);
  g_signal_connect(G_OBJECT(g->illum_y), "value-changed", G_CALLBACK(illum_xy_callback), self);
  gtk_box_pack_start(GTK_BOX(self->gui->widget), GTK_WIDGET(g->illum_y), FALSE, FALSE, 0);
 
  dt_bauhaus_slider_set_soft_range(g->temperature, 3000., 7000.);
  dt_bauhaus_slider_set_digits(g->temperature, 0);
  dt_bauhaus_slider_set_format(g->temperature, " K");
 
  g->gamut = dt_bauhaus_slider_from_params(self, "gamut");
  dt_bauhaus_slider_set_soft_max(g->gamut, 4.f);
 
  g->clip = dt_bauhaus_toggle_from_params(self, "clip");
 
  // Add the color mapping collapsible panel
 
  dt_gui_new_collapsible_section
    (&g->csspot,
     "plugins/darkroom/channelmixerrgb/expand_picker_mapping",
     _("spot color mapping"),
     GTK_BOX(self->gui->widget), GTK_PACK_END);
 
  gtk_widget_set_tooltip_text(g->csspot.expander, _("use a color checker target to autoset CAT and channels"));
 
  DT_BAUHAUS_COMBOBOX_NEW_FULL(dt_bauhaus_get_global(), g->spot_mode, DT_GUI_MODULE(self), N_("spot mode"),
                                _("\"correction\" automatically adjust the illuminant\n"
                                  "such that the input color is mapped to the target.\n"
                                  "\"measure\" simply shows how an input color is mapped by the CAT\n"
                                  "and can be used to sample a target."),
                                0, NULL, self,
                                N_("correction"),
                                N_("measure"));
  gtk_box_pack_start(GTK_BOX(g->csspot.container), GTK_WIDGET(g->spot_mode), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(g->spot_mode), "value-changed", G_CALLBACK(_spot_settings_changed_callback), self);
 
  gchar *label = N_("take channel mixing into account");
  g->use_mixing = gtk_check_button_new_with_label(_(label));
  gtk_label_set_ellipsize(GTK_LABEL(gtk_bin_get_child(GTK_BIN(g->use_mixing))), PANGO_ELLIPSIZE_END);
  gtk_widget_set_tooltip_text(g->use_mixing,
                              _("compute the target by taking the channel mixing into account.\n"
                                "if disabled, only the CAT is considered."));
  gtk_box_pack_start(GTK_BOX(g->csspot.container), GTK_WIDGET(g->use_mixing), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(g->use_mixing), "toggled", G_CALLBACK(_spot_settings_changed_callback), self);
 
  GtkWidget *hhbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_GUI_BOX_SPACING);
  GtkWidget *vvbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  gtk_box_pack_start(GTK_BOX(vvbox), dt_ui_section_label_new(_("input")), FALSE, FALSE, 0);
 
  g->origin_spot = GTK_WIDGET(gtk_drawing_area_new());
  gtk_widget_set_size_request(g->origin_spot, 2 * DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width),
                                              DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width));
  gtk_widget_set_tooltip_text(GTK_WIDGET(g->origin_spot),
                              _("the input color that should be mapped to the target"));
 
  g_signal_connect(G_OBJECT(g->origin_spot), "draw", G_CALLBACK(origin_color_draw), self);
  gtk_box_pack_start(GTK_BOX(vvbox), g->origin_spot, TRUE, TRUE, 0);
 
  g->Lch_origin = gtk_label_new(_("L: \tN/A\nh: \tN/A\nc: \tN/A"));
  gtk_widget_set_tooltip_text(GTK_WIDGET(g->Lch_origin),
                              _("these LCh coordinates are computed from CIE Lab 1976 coordinates"));
  gtk_box_pack_start(GTK_BOX(vvbox), GTK_WIDGET(g->Lch_origin), FALSE, FALSE, 0);
 
  gtk_box_pack_start(GTK_BOX(hhbox), GTK_WIDGET(vvbox), FALSE, FALSE, DT_BAUHAUS_SPACE);
 
  vvbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  gtk_box_pack_start(GTK_BOX(vvbox), dt_ui_section_label_new(_("target")), TRUE, TRUE, 0);
 
  g->target_spot = GTK_WIDGET(gtk_drawing_area_new());
  gtk_widget_set_size_request(g->target_spot, 2 * DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width),
                                              DT_PIXEL_APPLY_DPI(dt_bauhaus_get_global()->quad_width));
  gtk_widget_set_tooltip_text(GTK_WIDGET(g->target_spot),
                              _("the desired target color after mapping"));
 
  g_signal_connect(G_OBJECT(g->target_spot), "draw", G_CALLBACK(target_color_draw), self);
  gtk_box_pack_start(GTK_BOX(vvbox), g->target_spot, TRUE, TRUE, 0);
 
  g->lightness_spot = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., LIGHTNESS_MAX, 0, 0, 1);
  dt_bauhaus_widget_set_label(g->lightness_spot, N_("lightness"));
  dt_bauhaus_slider_set_format(g->lightness_spot, "%");
  dt_bauhaus_slider_set_default(g->lightness_spot, 50.f);
  gtk_box_pack_start(GTK_BOX(vvbox), GTK_WIDGET(g->lightness_spot), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(g->lightness_spot), "value-changed", G_CALLBACK(_spot_settings_changed_callback), self);
 
  g->hue_spot = dt_bauhaus_slider_new_with_range_and_feedback(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., HUE_MAX, 0, 0, 1, 0);
  dt_bauhaus_widget_set_label(g->hue_spot, N_("hue"));
  dt_bauhaus_slider_set_format(g->hue_spot, "\302\260");
  dt_bauhaus_slider_set_default(g->hue_spot, 0.f);
  gtk_box_pack_start(GTK_BOX(vvbox), GTK_WIDGET(g->hue_spot), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(g->hue_spot), "value-changed", G_CALLBACK(_spot_settings_changed_callback), self);
 
  g->chroma_spot = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., CHROMA_MAX, 0, 0, 1);
  dt_bauhaus_widget_set_label(g->chroma_spot, N_("chroma"));
  dt_bauhaus_slider_set_default(g->chroma_spot, 0.f);
  gtk_box_pack_start(GTK_BOX(vvbox), GTK_WIDGET(g->chroma_spot), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(g->chroma_spot), "value-changed", G_CALLBACK(_spot_settings_changed_callback), self);
 
  gtk_box_pack_start(GTK_BOX(hhbox), GTK_WIDGET(vvbox), TRUE, TRUE, DT_BAUHAUS_SPACE);
 
  gtk_box_pack_start(GTK_BOX(g->csspot.container), GTK_WIDGET(hhbox), FALSE, FALSE, 0);
 
  GtkWidget *mixer_page = dt_ui_notebook_page(g->notebook, N_("Mixer"), _("channel mixing"));
  g->mixer_mode = dt_bauhaus_combobox_new(dt_bauhaus_get_global(), DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->mixer_mode, N_("mode"));
  dt_bauhaus_combobox_add(g->mixer_mode, _("Complete"));
  dt_bauhaus_combobox_add(g->mixer_mode, _("Simple"));
  dt_bauhaus_combobox_add(g->mixer_mode, _("Primaries"));
  dt_bauhaus_combobox_add(g->mixer_mode, _("White-preserving"));
  gtk_widget_set_tooltip_text(g->mixer_mode,
                              _("complete exposes the original nine mixer coefficients.\n"
                                "simple rebuilds the normalized mixer as an exact chroma-plane rotation,\n"
                                "two signed stretches and two neutral couplings.\n"
                                "primaries rebuilds the mixer as a generalized primaries, white tint and gain model.\n"
                                "white-preserving rotates and saturates each primary around the white,\n"
                                "which stays exactly where it is."));
  gtk_box_pack_start(GTK_BOX(mixer_page), GTK_WIDGET(g->mixer_mode), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->mixer_mode), "value-changed", G_CALLBACK(_channelmixerrgb_mixer_mode_callback), self);
 
  g->mixer_stack = gtk_stack_new();
  gtk_stack_set_transition_type(GTK_STACK(g->mixer_stack), GTK_STACK_TRANSITION_TYPE_NONE);
  gtk_box_pack_start(GTK_BOX(mixer_page), GTK_WIDGET(g->mixer_stack), FALSE, FALSE, 0);
 
  GtkWidget *mixer_complete = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_stack_add_named(GTK_STACK(g->mixer_stack), mixer_complete, "complete");
 
  GtkWidget *first, *second, *third;
#define MIXER_ROW(var, short, section, swap)                                   \
  gtk_box_pack_start(GTK_BOX(mixer_complete), dt_ui_section_label_new(section), FALSE, FALSE, 0); \
  self->gui->widget = mixer_complete;                                               \
  first = dt_bauhaus_slider_from_params(self, swap ? #var "[2]" : #var "[0]");\
  dt_bauhaus_slider_set_digits(first, 3);                                     \
  dt_bauhaus_widget_set_label(first, N_("input R"));                          \
  second = dt_bauhaus_slider_from_params(self, #var "[1]");                   \
  dt_bauhaus_slider_set_digits(second, 3);                                    \
  dt_bauhaus_widget_set_label(second, N_("input G"));                         \
  third = dt_bauhaus_slider_from_params(self, swap ? #var "[0]" : #var "[2]");\
  dt_bauhaus_slider_set_digits(third, 3);                                     \
  dt_bauhaus_widget_set_label(third, N_("input B"));                          \
  g->scale_##var##_R = swap ? third : first;                                  \
  g->scale_##var##_G = second;                                                \
  g->scale_##var##_B = swap ? first : third;                                  \
  g->normalize_##short = dt_bauhaus_toggle_from_params(self, "normalize_" #short);
 
  MIXER_ROW(red, R, _("output red"), FALSE)
  MIXER_ROW(green, G, _("output green"), FALSE)
  MIXER_ROW(blue, B, _("output blue"), FALSE)
 
  GtkWidget *mixer_simple = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_stack_add_named(GTK_STACK(g->mixer_stack), mixer_simple, "simple");
 
  g->simple_theta = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->simple_theta, N_("global hue rotation"));
  dt_bauhaus_slider_set_factor(g->simple_theta, 180.f);
  dt_bauhaus_slider_set_format(g->simple_theta, "\302\260");
  gtk_widget_set_tooltip_text(g->simple_theta, _("global rotation of the normalized chroma plane."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_theta), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_theta), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_simple), dt_ui_section_label_new(_("chroma")), FALSE, FALSE, 0);
 
  g->simple_psi = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->simple_psi, N_("chroma (u,v) axes orientation"));
  dt_bauhaus_slider_set_factor(g->simple_psi, 90.f);
  dt_bauhaus_slider_set_format(g->simple_psi, "\302\260");
  gtk_widget_set_tooltip_text(g->simple_psi, _("orientation of the principal stretch axes in the chroma plane."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_psi), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_psi), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  g->simple_stretch_1 = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.5f, 1.5f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->simple_stretch_1, N_("u stretch"));
  gtk_widget_set_tooltip_text(g->simple_stretch_1, _("stretch along the first principal chroma axis. 0 neutralizes chroma, 1 keeps identity, -1 reverses chroma and +/-1.5 add contrast."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_stretch_1), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_stretch_1), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  g->simple_stretch_2 = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.5f, 1.5f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->simple_stretch_2, N_("v stretch"));
  gtk_widget_set_tooltip_text(g->simple_stretch_2, _("stretch along the second principal chroma axis. 0 neutralizes chroma, 1 keeps identity, -1 reverses chroma and +/-1.5 add contrast."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_stretch_2), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_stretch_2), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_simple), dt_ui_section_label_new(_("achromatic coupling")), FALSE, FALSE, 0);
 
  g->simple_coupling_2 = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->simple_coupling_2, N_("achromatic coupling hue"));
  dt_bauhaus_slider_set_factor(g->simple_coupling_2, 180.f);
  dt_bauhaus_slider_set_format(g->simple_coupling_2, "\302\260");
  gtk_widget_set_tooltip_text(g->simple_coupling_2, _("chroma direction, in the fixed chroma basis, that is coupled into the achromatic axis."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_coupling_2), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_coupling_2), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  g->simple_coupling_1 = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->simple_coupling_1, N_("achromatic coupling amount"));
  gtk_widget_set_tooltip_text(g->simple_coupling_1, _("strength of the chroma-to-achromatic coupling in the fixed chroma basis."));
  gtk_box_pack_start(GTK_BOX(mixer_simple), GTK_WIDGET(g->simple_coupling_1), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->simple_coupling_1), "value-changed", G_CALLBACK(_channelmixerrgb_simple_slider_callback), self);
 
  GtkWidget *mixer_primaries = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_stack_add_named(GTK_STACK(g->mixer_stack), mixer_primaries, "primaries");
 
  gtk_box_pack_start(GTK_BOX(mixer_primaries), dt_ui_section_label_new(_("achromatic axis")), FALSE, FALSE, 0);
 
  g->primaries_achromatic_hue = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -2.f, 2.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->primaries_achromatic_hue, N_("white hue"));
  dt_bauhaus_slider_set_factor(g->primaries_achromatic_hue, 90.f);
  dt_bauhaus_slider_set_format(g->primaries_achromatic_hue, "\302\260");
  gtk_widget_set_tooltip_text(g->primaries_achromatic_hue,
                              _("rotate the custom white vector around the D50 white of the current mixer basis."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_achromatic_hue), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_achromatic_hue), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  g->primaries_achromatic_purity = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0.f, 2.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->primaries_achromatic_purity, N_("white purity"));
  gtk_widget_set_tooltip_text(g->primaries_achromatic_purity,
                              _("distance of the custom white vector from the D50 white within the current mixer basis."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_achromatic_purity), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_achromatic_purity), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_primaries), dt_ui_section_label_new(_("red primary")), FALSE, FALSE, 0);
 
  g->primaries_red_hue = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->primaries_red_hue, N_("red hue"));
  dt_bauhaus_slider_set_factor(g->primaries_red_hue, 90.f);
  dt_bauhaus_slider_set_format(g->primaries_red_hue, "\302\260");
  gtk_widget_set_tooltip_text(g->primaries_red_hue,
                              _("rotate the first basis vector around the D50 white of the current mixer basis."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_red_hue), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_red_hue), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  g->primaries_red_purity = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0.f, 2.f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->primaries_red_purity, N_("red purity"));
  gtk_widget_set_tooltip_text(g->primaries_red_purity,
                              _("radial scaling of the first basis vector inside the affine primaries footprint."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_red_purity), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_red_purity), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_primaries), dt_ui_section_label_new(_("green primary")), FALSE, FALSE, 0);
 
  g->primaries_green_hue = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->primaries_green_hue, N_("green hue"));
  dt_bauhaus_slider_set_factor(g->primaries_green_hue, 90.f);
  dt_bauhaus_slider_set_format(g->primaries_green_hue, "\302\260");
  gtk_widget_set_tooltip_text(g->primaries_green_hue,
                              _("rotate the second basis vector around the D50 white of the current mixer basis."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_green_hue), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_green_hue), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  g->primaries_green_purity = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0.f, 2.f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->primaries_green_purity, N_("green purity"));
  gtk_widget_set_tooltip_text(g->primaries_green_purity,
                              _("radial scaling of the second basis vector inside the affine primaries footprint."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_green_purity), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_green_purity), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_primaries), dt_ui_section_label_new(_("blue primary")), FALSE, FALSE, 0);
 
  g->primaries_blue_hue = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);
  dt_bauhaus_widget_set_label(g->primaries_blue_hue, N_("blue hue"));
  dt_bauhaus_slider_set_factor(g->primaries_blue_hue, 90.f);
  dt_bauhaus_slider_set_format(g->primaries_blue_hue, "\302\260");
  gtk_widget_set_tooltip_text(g->primaries_blue_hue,
                              _("rotate the third basis vector around the D50 white of the current mixer basis."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_blue_hue), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_blue_hue), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  g->primaries_blue_purity = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0.f, 2.f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->primaries_blue_purity, N_("blue purity"));
  gtk_widget_set_tooltip_text(g->primaries_blue_purity,
                              _("radial scaling of the third basis vector inside the affine primaries footprint."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_blue_purity), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_blue_purity), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  gtk_box_pack_start(GTK_BOX(mixer_primaries), dt_ui_section_label_new(_("gain correction")), FALSE, FALSE, 0);
 
  g->primaries_gain = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -8.f, 8.f, 0, 1.f, 3);
  dt_bauhaus_widget_set_label(g->primaries_gain, N_("gain"));
  gtk_widget_set_tooltip_text(g->primaries_gain,
                              _("global gain multiplying the custom white vector after the affine primaries transform."));
  gtk_box_pack_start(GTK_BOX(mixer_primaries), GTK_WIDGET(g->primaries_gain), FALSE, FALSE, 0);
  g_signal_connect(G_OBJECT(g->primaries_gain), "value-changed",
                   G_CALLBACK(_channelmixerrgb_primaries_slider_callback), self);
 
  GtkWidget *mixer_white_preserving = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_stack_add_named(GTK_STACK(g->mixer_stack), mixer_white_preserving, "white-preserving");
 
#define WHITE_PRESERVING_PRIMARY(var, section, rotation_label, rotation_tooltip, saturation_label,             \
                                 saturation_tooltip)                                                          \
  gtk_box_pack_start(GTK_BOX(mixer_white_preserving), dt_ui_section_label_new(section), FALSE, FALSE, 0);      \
  g->white_preserving_##var##_rotation                                                                        \
      = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -1.f, 1.f, 0, 0, 3);    \
  dt_bauhaus_widget_set_label(g->white_preserving_##var##_rotation, rotation_label);                          \
  dt_bauhaus_slider_set_factor(g->white_preserving_##var##_rotation, 90.f);                                   \
  dt_bauhaus_slider_set_format(g->white_preserving_##var##_rotation, "\302\260");                             \
  gtk_widget_set_tooltip_text(g->white_preserving_##var##_rotation, rotation_tooltip);                        \
  gtk_box_pack_start(GTK_BOX(mixer_white_preserving), GTK_WIDGET(g->white_preserving_##var##_rotation), FALSE,\
                     FALSE, 0);                                                                               \
  g_signal_connect(G_OBJECT(g->white_preserving_##var##_rotation), "value-changed",                           \
                   G_CALLBACK(_channelmixerrgb_white_preserving_slider_callback), self);                      \
  /* -100%/+100% is the travel this control is meant to be used over, but a matrix hand-built  */           \
  /* in complete mode can legitimately push a primary further out. Keep the hard range wider so */           \
  /* the page reports such a matrix instead of clamping and quietly lying about it.             */           \
  g->white_preserving_##var##_saturation                                                                      \
      = dt_bauhaus_slider_new_with_range(dt_bauhaus_get_global(), DT_GUI_MODULE(self), -4.f, 4.f, 0, 0, 3);    \
  dt_bauhaus_slider_set_soft_range(g->white_preserving_##var##_saturation, -1.f, 1.f);                        \
  dt_bauhaus_widget_set_label(g->white_preserving_##var##_saturation, saturation_label);                      \
  /* On a range under 10, a "%" format makes bauhaus scale by 100 and take two digits off by     */           \
  /* itself. Do not also set a factor, and leave it enough digits to take : it subtracts them    */           \
  /* unconditionally, and a negative digit count used to hang the whole GUI in ipow().           */           \
  dt_bauhaus_slider_set_format(g->white_preserving_##var##_saturation, "%");                                  \
  gtk_widget_set_tooltip_text(g->white_preserving_##var##_saturation, saturation_tooltip);                    \
  gtk_box_pack_start(GTK_BOX(mixer_white_preserving), GTK_WIDGET(g->white_preserving_##var##_saturation),      \
                     FALSE, FALSE, 0);                                                                        \
  g_signal_connect(G_OBJECT(g->white_preserving_##var##_saturation), "value-changed",                         \
                   G_CALLBACK(_channelmixerrgb_white_preserving_slider_callback), self);
 
  WHITE_PRESERVING_PRIMARY(red, _("red primary"), N_("red rotation"),
                           _("rotate the red primary around the white of the current mixer basis.\n"
                             "the white itself is left exactly where it is."),
                           N_("red saturation"),
                           _("scale the red primary's distance to the white of the current mixer basis.\n"
                             "-100% collapses it onto the white, +100% doubles it."))
  WHITE_PRESERVING_PRIMARY(green, _("green primary"), N_("green rotation"),
                           _("rotate the green primary around the white of the current mixer basis.\n"
                             "the white itself is left exactly where it is."),
                           N_("green saturation"),
                           _("scale the green primary's distance to the white of the current mixer basis.\n"
                             "-100% collapses it onto the white, +100% doubles it."))
  WHITE_PRESERVING_PRIMARY(blue, _("blue primary"), N_("blue rotation"),
                           _("rotate the blue primary around the white of the current mixer basis.\n"
                             "the white itself is left exactly where it is."),
                           N_("blue saturation"),
                           _("scale the blue primary's distance to the white of the current mixer basis.\n"
                             "-100% collapses it onto the white, +100% doubles it."))
 
#undef WHITE_PRESERVING_PRIMARY
 
  GtkWidget *outputs_page = dt_ui_notebook_page(g->notebook, N_("Outputs"),
                                                _("output colorfulness, brightness and B&W mixing"));
  self->gui->widget = outputs_page;
 
#define OUTPUT_SECTION(var, short, section, swap)                              \
  gtk_box_pack_start(GTK_BOX(outputs_page), dt_ui_section_label_new(section), FALSE, FALSE, 0); \
                                                                              \
  first = dt_bauhaus_slider_from_params(self, swap ? #var "[2]" : #var "[0]");\
  dt_bauhaus_slider_set_digits(first, 3);                                     \
  dt_bauhaus_widget_set_label(first, N_("input R"));                          \
                                                                              \
  second = dt_bauhaus_slider_from_params(self, #var "[1]");                   \
  dt_bauhaus_slider_set_digits(second, 3);                                    \
  dt_bauhaus_widget_set_label(second, N_("input G"));                         \
                                                                              \
  third = dt_bauhaus_slider_from_params(self, swap ? #var "[0]" : #var "[2]");\
  dt_bauhaus_slider_set_digits(third, 3);                                     \
  dt_bauhaus_widget_set_label(third, N_("input B"));                          \
                                                                              \
  g->scale_##var##_R = swap ? third : first;                                  \
  g->scale_##var##_G = second;                                                \
  g->scale_##var##_B = swap ? first : third;                                  \
                                                                              \
  g->normalize_##short = dt_bauhaus_toggle_from_params(self, "normalize_" #short);
 
  OUTPUT_SECTION(saturation, sat, _("colorfulness"), FALSE)
  g->saturation_version = dt_bauhaus_combobox_from_params(self, "version");
  OUTPUT_SECTION(lightness, light, _("brightness"), FALSE)
  OUTPUT_SECTION(grey, grey, _("B&W"), FALSE)
 
  // start building top level widget
  self->gui->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  gtk_box_pack_start(GTK_BOX(self->gui->widget), GTK_WIDGET(g->notebook), FALSE, FALSE, 0);
  const int saved_page = dt_conf_get_int("plugins/darkroom/channelmixerrgb/gui_page");
  const int active_page = saved_page > 2 ? 2 : CLAMP(saved_page, 0, 2);
  gtk_widget_show(gtk_notebook_get_nth_page(g->notebook, active_page));
  gtk_notebook_set_current_page(g->notebook, active_page);
 
  // Add the color checker collapsible panel
 
  dt_gui_new_collapsible_section
    (&g->cs,
     "plugins/darkroom/channelmixerrgb/expand_values",
     _("calibrate with a color checker"),
     GTK_BOX(self->gui->widget), GTK_PACK_END);
 
  gtk_widget_set_tooltip_text(g->cs.toggle,
                              _("use a color checker target to autoset CAT and channels"));
  g_signal_connect(G_OBJECT(g->cs.toggle), "toggled", G_CALLBACK(start_profiling_callback), self);
 
  GtkWidget *collapsible = GTK_WIDGET(g->cs.container);
 
  gchar *tip_files_loc = NULL;
  {
    char confdir[DT_PATH_MAX] = { 0 };
    dt_loc_get_user_config_dir(confdir, sizeof(confdir));
    
    gchar *user_CGATS_dir = g_build_filename(confdir, "color", "checker", NULL);
    tip_files_loc = g_strdup_printf(_("'%s'"), user_CGATS_dir);
    dt_free(user_CGATS_dir);
  }
 
  g->checkers_list = dt_bauhaus_combobox_new(dt_bauhaus_get_global(), DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->checkers_list, N_("Chart"));
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->checkers_list), TRUE, TRUE, 0);
  dt_bauhaus_combobox_set(g->checkers_list, 0);
  gchar *tooltip = g_strdup_printf(_("Choose the vendor and the type of your chart.\n"
                                      ".cht files in %s."), tip_files_loc);
  gtk_widget_set_tooltip_text(g->checkers_list, tooltip);
  dt_free(tooltip);
  g_signal_connect(G_OBJECT(g->checkers_list), "value-changed", G_CALLBACK(checker_changed_callback), (gpointer)self);
 
  g->checkers_color_list = dt_bauhaus_combobox_new(dt_bauhaus_get_global(), DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->checkers_color_list, N_("Chart color"));
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->checkers_color_list), TRUE, TRUE, 0);
 
  dt_bauhaus_combobox_set(g->checkers_color_list, 0);
  tooltip = g_strdup_printf(_("Choose the definition of your chart.\n"
                                      "CGATS.17 files in %s."), tip_files_loc);
  gtk_widget_set_tooltip_text(g->checkers_color_list, tooltip);
  dt_free(tooltip);
  g_signal_connect(G_OBJECT(g->checkers_color_list), "value-changed", G_CALLBACK(checker_color_changed_callback), (gpointer)self);
  
  tooltip = g_markup_printf_escaped(_("<i>No CGATS.17 color file matches the selected chart.\n"
                                      "Add a compatible CGATS.17 file to <b>%s</b>.</i>"), tip_files_loc);
  g->checker_msg = gtk_label_new(NULL);
  gtk_label_set_markup(GTK_LABEL(g->checker_msg), tooltip);
  dt_free(tooltip);
  gtk_label_set_line_wrap(GTK_LABEL(g->checker_msg), TRUE);
  gtk_label_set_line_wrap_mode(GTK_LABEL(g->checker_msg), PANGO_WRAP_WORD);
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->checker_msg), FALSE, TRUE, 0);
  gtk_widget_set_visible(g->checker_msg, FALSE);
  dt_free(tip_files_loc);
 
 
 
  DT_BAUHAUS_COMBOBOX_NEW_FULL(dt_bauhaus_get_global(), g->optimize, DT_GUI_MODULE(self), N_("optimize for"),
                                _("choose the colors that will be optimized with higher priority.\n"
                                  "neutral colors gives the lowest average delta E but a high maximum delta E\n"
                                  "saturated colors gives the lowest maximum delta E but a high average delta E\n"
                                  "none is a trade-off between both\n"
                                  "the others are special behaviours to protect some hues"),
                                0, optimize_changed_callback, self,
                                N_("none"),
                                N_("neutral colors"),
                                N_("saturated colors"),
                                N_("skin and soil colors"),
                                N_("foliage colors"),
                                N_("sky and water colors"),
                                N_("average delta E"),
                                N_("maximum delta E"));
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->optimize), TRUE, TRUE, 0);
 
  g->safety = dt_bauhaus_slider_new_with_range_and_feedback(dt_bauhaus_get_global(), DT_GUI_MODULE(self), 0., 1., 0, 0.5, 3, TRUE);
  dt_bauhaus_widget_set_label(g->safety, N_("patch scale"));
  gtk_widget_set_tooltip_text(g->safety, _("reduce the radius of the patches to select the more or less central part.\n"
                                           "useful when the perspective correction is sloppy or\n"
                                           "the patches frame cast a shadows on the edges of the patch." ));
  g_signal_connect(G_OBJECT(g->safety), "value-changed", G_CALLBACK(safety_changed_callback), self);
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->safety), TRUE, TRUE, 0);
 
  g->label_delta_E = dt_ui_label_new("");
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(g->label_delta_E), TRUE, TRUE, 0);
  gtk_widget_set_tooltip_text(g->label_delta_E, _("the delta E is using the CIE 2000 formula"));
 
  GtkWidget *toolbar = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_GUI_BOX_SPACING);
 
  g->button_commit = dtgtk_button_new(dtgtk_cairo_paint_check_mark, 0, NULL);
  gtk_box_pack_end(GTK_BOX(toolbar), GTK_WIDGET(g->button_commit), FALSE, FALSE, 0);
  gtk_widget_set_tooltip_text(g->button_commit, _("accept the computed profile and set it in the module"));
  g_signal_connect(G_OBJECT(g->button_commit), "button-press-event", G_CALLBACK(commit_profile_callback), (gpointer)self);
 
  g->button_profile = dtgtk_button_new(dtgtk_cairo_paint_refresh, 0, NULL);
  g_signal_connect(G_OBJECT(g->button_profile), "button-press-event", G_CALLBACK(run_profile_callback), (gpointer)self);
  gtk_widget_set_tooltip_text(g->button_profile, _("recompute the profile"));
  gtk_box_pack_end(GTK_BOX(toolbar), GTK_WIDGET(g->button_profile), FALSE, FALSE, 0);
 
  g->button_validate = dtgtk_button_new(dtgtk_cairo_paint_softproof, 0, NULL);
  g_signal_connect(G_OBJECT(g->button_validate), "button-press-event", G_CALLBACK(run_validation_callback), (gpointer)self);
  gtk_widget_set_tooltip_text(g->button_validate, _("check the output delta E"));
  gtk_box_pack_end(GTK_BOX(toolbar), GTK_WIDGET(g->button_validate), FALSE, FALSE, 0);
 
  gtk_box_pack_start(GTK_BOX(collapsible), GTK_WIDGET(toolbar), FALSE, FALSE, 0);
}
 
void gui_cleanup(struct dt_iop_module_t *self)
{
  self->request_color_pick = DT_REQUEST_COLORPICK_OFF;
  DT_DEBUG_CONTROL_SIGNAL_DISCONNECT(dt_control_signal_get_global(),
                                     G_CALLBACK(_develop_ui_pipe_finished_callback), self);
  DT_DEBUG_CONTROL_SIGNAL_DISCONNECT(dt_control_signal_get_global(), G_CALLBACK(_preview_pipe_finished_callback), self);
 
  dt_iop_channelmixer_rgb_gui_data_t *g = (dt_iop_channelmixer_rgb_gui_data_t *)dt_iop_gui_data(self);
  dt_conf_set_int("plugins/darkroom/channelmixerrgb/gui_page", gtk_notebook_get_current_page (g->notebook));
 
  if(g->delta_E_in)
  {
    dt_free_align(g->delta_E_in);
    g->delta_E_in = NULL;
  }
 
  dt_free(g->delta_E_label_text);
 
  dt_colorchecker_label_list_cleanup(&(g->colorcheckers));
  dt_colorchecker_label_list_cleanup(&(g->colorcheckers_all_color));
  g_list_free(g->colorcheckers_color); // data pointers are already freed by the cleanup function for colorcheckers_all_color
 
  dt_colorchecker_cleanup(g->checker);
 
  IOP_GUI_FREE;
}
 
// clang-format off
// modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
// vim: shiftwidth=2 expandtab tabstop=2 cindent
// kate: tab-indents: off; indent-width 2; replace-tabs on; indent-mode cstyle; remove-trailing-spaces modified;
// clang-format on