iop/colorchecker.c

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/*
    This file is part of darktable,
    Copyright (C) 2016-2017 johannes hanika.
    Copyright (C) 2016 Roman Lebedev.
    Copyright (C) 2016, 2018-2019 Tobias Ellinghaus.
    Copyright (C) 2016-2017 Ulrich Pegelow.
    Copyright (C) 2017 Heiko Bauke.
    Copyright (C) 2017 luzpaz.
    Copyright (C) 2018-2020, 2022-2023, 2025-2026 Aurélien PIERRE.
    Copyright (C) 2018 Edgardo Hoszowski.
    Copyright (C) 2018 Maurizio Paglia.
    Copyright (C) 2018-2022 Pascal Obry.
    Copyright (C) 2018 rawfiner.
    Copyright (C) 2019 Andreas Schneider.
    Copyright (C) 2019 Bill Ferguson.
    Copyright (C) 2019-2022 Diederik Ter Rahe.
    Copyright (C) 2019 Diederik ter Rahe.
    Copyright (C) 2019 mepi0011.
    Copyright (C) 2020 Aldric Renaudin.
    Copyright (C) 2020 Chris Elston.
    Copyright (C) 2020-2021 Hubert Kowalski.
    Copyright (C) 2020-2021 Ralf Brown.
    Copyright (C) 2021 Dan Torop.
    Copyright (C) 2021 Frank Loemker.
    Copyright (C) 2021 lhietal.
    Copyright (C) 2022 Hanno Schwalm.
    Copyright (C) 2022 Martin Bařinka.
    Copyright (C) 2022 Philipp Lutz.
    
    darktable 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.
    
    darktable 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 darktable.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "common/darktable.h"
#include "bauhaus/bauhaus.h"
#include "common/colorspaces_inline_conversions.h"
#include "common/math.h"
#include "common/opencl.h"
#include "common/exif.h"
#include "control/control.h"
#include "develop/develop.h"
#include "develop/imageop.h"
#include "develop/imageop_math.h"
#include "develop/openmp_maths.h"
#include "develop/tiling.h"
#include "dtgtk/drawingarea.h"
 
#include "gui/gtk.h"
#include "gui/presets.h"
#include "iop/iop_api.h"
#include "iop/gaussian_elimination.h"
 
#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
 
#include <gtk/gtk.h>
#include <inttypes.h>
 
DT_MODULE_INTROSPECTION(2, dt_iop_colorchecker_params_t)
 
static const int colorchecker_patches = 24;
static const float colorchecker_Lab[] =
{ // from argyll ColorChecker.cie
 37.99,   13.56,  14.06, // dark skin
 65.71,   18.13,  17.81, // light skin
 49.93,   -4.88, -21.93, // blue sky
 43.14,  -13.10,  21.91, // foliage
 55.11,    8.84, -25.40, // blue flower
 70.72,  -33.40, -0.20 , // bluish green
 62.66,   36.07,  57.10, // orange
 40.02,   10.41, -45.96, // purple red
 51.12,   48.24,  16.25, // moderate red
 30.33,   22.98, -21.59, // purple
 72.53,  -23.71,  57.26, // yellow green
 71.94,  19.36 ,  67.86, // orange yellow
 28.78,  14.18 , -50.30, // blue
 55.26,  -38.34,  31.37, // green
 42.10,  53.38 ,  28.19, // red
 81.73,  4.04  ,  79.82, // yellow
 51.94,  49.99 , -14.57, // magenta
 51.04,  -28.63, -28.64, // cyan
 96.54,  -0.43 ,  1.19 , // white
 81.26,  -0.64 , -0.34 , // neutral 8
 66.77,  -0.73 , -0.50 , // neutral 65
 50.87,  -0.15 , -0.27 , // neutral 5
 35.66,  -0.42 , -1.23 , // neutral 35
 20.46,  -0.08 , -0.97   // black
};
 
// we came to the conclusion that more than 7x7 patches will not be
// manageable in the gui. the fitting experiments show however that you
// can do significantly better with 49 than you can with 24 patches,
// especially when considering max delta E.
#define MAX_PATCHES 49
typedef struct dt_iop_colorchecker_params_t
{
  float source_L[MAX_PATCHES];
  float source_a[MAX_PATCHES];
  float source_b[MAX_PATCHES];
  float target_L[MAX_PATCHES];
  float target_a[MAX_PATCHES];
  float target_b[MAX_PATCHES];
  int32_t num_patches;
} dt_iop_colorchecker_params_t;
 
typedef struct dt_iop_colorchecker_gui_data_t
{
  GtkWidget *area, *combobox_patch, *scale_L, *scale_a, *scale_b, *scale_C, *combobox_target;
  int patch, drawn_patch;
  int absolute_target; // 0: show relative offsets in sliders, 1: show absolute Lab values
} dt_iop_colorchecker_gui_data_t;
 
typedef struct dt_iop_colorchecker_data_t
{
  int32_t num_patches;
  float source_Lab[3*MAX_PATCHES];
  float coeff_L[MAX_PATCHES+4];
  float coeff_a[MAX_PATCHES+4];
  float coeff_b[MAX_PATCHES+4];
} dt_iop_colorchecker_data_t;
 
typedef struct dt_iop_colorchecker_global_data_t
{
  int kernel_colorchecker;
} dt_iop_colorchecker_global_data_t;
 
 
const char *name()
{
  return _("color look up table");
}
 
const char *aliases()
{
  return _("profile|lut|color grading");
}
 
const char **description(struct dt_iop_module_t *self)
{
  return dt_iop_set_description(self, _("perform color space corrections and apply looks"),
                                      _("corrective or creative"),
                                      _("linear or non-linear, Lab, display-referred"),
                                      _("defined by profile, Lab"),
                                      _("linear or non-linear, Lab, display-referred"));
}
 
 
int default_group()
{
  return IOP_GROUP_COLOR;
}
 
int flags()
{
  return IOP_FLAGS_SUPPORTS_BLENDING | IOP_FLAGS_ALLOW_TILING | IOP_FLAGS_DEPRECATED;
}
 
int default_colorspace(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece)
{
  return IOP_CS_LAB;
}
 
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)
{
  static const float colorchecker_Lab_v1[] = {
    39.19, 13.76,  14.29,  // dark skin
    65.18, 19.00,  17.32,  // light skin
    49.46, -4.23,  -22.95, // blue sky
    42.85, -13.33, 22.12,  // foliage
    55.18, 9.44,   -24.94, // blue flower
    70.36, -32.77, -0.04,  // bluish green
    62.92, 35.49,  57.10,  // orange
    40.75, 11.41,  -46.03, // purple red
    52.10, 48.11,  16.89,  // moderate red
    30.67, 21.19,  -20.81, // purple
    73.08, -23.55, 56.97,  // yellow green
    72.43, 17.48,  68.20,  // orange yellow
    30.97, 12.67,  -46.30, // blue
    56.43, -40.66, 31.94,  // green
    43.40, 50.68,  28.84,  // red
    82.45, 2.41,   80.25,  // yellow
    51.98, 50.68,  -14.84, // magenta
    51.02, -27.63, -28.03, // cyan
    95.97, -0.40,  1.24,   // white
    81.10, -0.83,  -0.43,  // neutral 8
    66.81, -1.08,  -0.70,  // neutral 65
    50.98, -0.19,  -0.30,  // neutral 5
    35.72, -0.69,  -1.11,  // neutral 35
    21.46, 0.06,   -0.95,  // black
  };
 
  typedef struct dt_iop_colorchecker_params_v1_t
  {
    float target_L[24];
    float target_a[24];
    float target_b[24];
  } dt_iop_colorchecker_params_v1_t;
 
  if(old_version == 1 && new_version == 2)
  {
    dt_iop_colorchecker_params_v1_t *p1 = (dt_iop_colorchecker_params_v1_t *)old_params;
    dt_iop_colorchecker_params_t  *p2 = (dt_iop_colorchecker_params_t  *)new_params;
 
    p2->num_patches = 24;
    for(int k=0;k<24;k++)
    {
      p2->target_L[k] = p1->target_L[k];
      p2->target_a[k] = p1->target_a[k];
      p2->target_b[k] = p1->target_b[k];
      p2->source_L[k] = colorchecker_Lab_v1[3 * k + 0];
      p2->source_a[k] = colorchecker_Lab_v1[3 * k + 1];
      p2->source_b[k] = colorchecker_Lab_v1[3 * k + 2];
    }
    return 0;
  }
  return 1;
}
 
void init_presets(dt_iop_module_so_t *self)
{
  dt_iop_colorchecker_params_t p;
  memset(&p, 0, sizeof(p));
  p.num_patches = 24;
  p.target_L[ 0] = p.source_L[ 0] = 17.460945129394531;
  p.target_L[ 1] = p.source_L[ 1] = 26.878498077392578;
  p.target_L[ 2] = p.source_L[ 2] = 34.900054931640625;
  p.target_L[ 3] = p.source_L[ 3] = 21.692604064941406;
  p.target_L[ 4] = p.source_L[ 4] = 32.18853759765625;
  p.target_L[ 5] = p.source_L[ 5] = 62.531227111816406;
  p.target_L[ 6] = p.source_L[ 6] = 18.933284759521484;
  p.target_L[ 7] = p.source_L[ 7] = 53.936111450195312;
  p.target_L[ 8] = p.source_L[ 8] = 69.154266357421875;
  p.target_L[ 9] = p.source_L[ 9] = 43.381229400634766;
  p.target_L[10] = p.source_L[10] = 57.797889709472656;
  p.target_L[11] = p.source_L[11] = 73.27630615234375;
  p.target_L[12] = p.source_L[12] = 53.175498962402344;
  p.target_L[13] = p.source_L[13] = 49.111373901367188;
  p.target_L[14] = p.source_L[14] = 63.169830322265625;
  p.target_L[15] = p.source_L[15] = 61.896102905273438;
  p.target_L[16] = p.source_L[16] = 67.852409362792969;
  p.target_L[17] = p.source_L[17] = 72.489517211914062;
  p.target_L[18] = p.source_L[18] = 70.935714721679688;
  p.target_L[19] = p.source_L[19] = 70.173004150390625;
  p.target_L[20] = p.source_L[20] = 77.78826904296875;
  p.target_L[21] = p.source_L[21] = 76.070747375488281;
  p.target_L[22] = p.source_L[22] = 68.645004272460938;
  p.target_L[23] = p.source_L[23] = 74.502906799316406;
  p.target_a[ 0] = p.source_a[ 0] = 8.4928874969482422;
  p.target_a[ 1] = p.source_a[ 1] = 27.94782829284668;
  p.target_a[ 2] = p.source_a[ 2] = 43.8824462890625;
  p.target_a[ 3] = p.source_a[ 3] = 16.723676681518555;
  p.target_a[ 4] = p.source_a[ 4] = 39.174972534179688;
  p.target_a[ 5] = p.source_a[ 5] = 24.966419219970703;
  p.target_a[ 6] = p.source_a[ 6] = 8.8226642608642578;
  p.target_a[ 7] = p.source_a[ 7] = 34.451812744140625;
  p.target_a[ 8] = p.source_a[ 8] = 18.39008903503418;
  p.target_a[ 9] = p.source_a[ 9] = 28.272598266601562;
  p.target_a[10] = p.source_a[10] = 10.193824768066406;
  p.target_a[11] = p.source_a[11] = 13.241470336914062;
  p.target_a[12] = p.source_a[12] = 43.655307769775391;
  p.target_a[13] = p.source_a[13] = 23.247600555419922;
  p.target_a[14] = p.source_a[14] = 23.308664321899414;
  p.target_a[15] = p.source_a[15] = 11.138319969177246;
  p.target_a[16] = p.source_a[16] = 18.200069427490234;
  p.target_a[17] = p.source_a[17] = 15.363990783691406;
  p.target_a[18] = p.source_a[18] = 11.173545837402344;
  p.target_a[19] = p.source_a[19] = 11.313735961914062;
  p.target_a[20] = p.source_a[20] = 15.059500694274902;
  p.target_a[21] = p.source_a[21] = 4.7686996459960938;
  p.target_a[22] = p.source_a[22] = 3.0603706836700439;
  p.target_a[23] = p.source_a[23] = -3.687053918838501;
  p.target_b[ 0] = p.source_b[ 0] = -0.023579597473144531;
  p.target_b[ 1] = p.source_b[ 1] = 14.991056442260742;
  p.target_b[ 2] = p.source_b[ 2] = 26.443553924560547;
  p.target_b[ 3] = p.source_b[ 3] = 7.3905587196350098;
  p.target_b[ 4] = p.source_b[ 4] = 23.309671401977539;
  p.target_b[ 5] = p.source_b[ 5] = 19.262432098388672;
  p.target_b[ 6] = p.source_b[ 6] = 3.136211633682251;
  p.target_b[ 7] = p.source_b[ 7] = 31.949621200561523;
  p.target_b[ 8] = p.source_b[ 8] = 16.144514083862305;
  p.target_b[ 9] = p.source_b[ 9] = 25.893926620483398;
  p.target_b[10] = p.source_b[10] = 12.271202087402344;
  p.target_b[11] = p.source_b[11] = 16.763805389404297;
  p.target_b[12] = p.source_b[12] = 53.904998779296875;
  p.target_b[13] = p.source_b[13] = 36.537342071533203;
  p.target_b[14] = p.source_b[14] = 32.930683135986328;
  p.target_b[15] = p.source_b[15] = 19.008804321289062;
  p.target_b[16] = p.source_b[16] = 32.259223937988281;
  p.target_b[17] = p.source_b[17] = 25.815582275390625;
  p.target_b[18] = p.source_b[18] = 26.509498596191406;
  p.target_b[19] = p.source_b[19] = 40.572704315185547;
  p.target_b[20] = p.source_b[20] = 88.354469299316406;
  p.target_b[21] = p.source_b[21] = 33.434604644775391;
  p.target_b[22] = p.source_b[22] = 9.5750093460083008;
  p.target_b[23] = p.source_b[23] = 41.285167694091797;
  dt_gui_presets_add_generic(_("it8 skin tones"), self->op,
                             self->version(), &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // helmholtz/kohlrausch effect applied to black and white conversion.
  // implemented by wmader as an iop and matched as a clut for increased
  // flexibility. this was done using ansel-chart and this is copied
  // from the resulting dtstyle output file:
  const char *hk_params_input =
    "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";
  int params_len = 0;
  uint8_t *hk_params = dt_exif_xmp_decode(
      hk_params_input, strlen(hk_params_input), &params_len);
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(hk_params);
  dt_gui_presets_add_generic(_("helmholtz/kohlrausch monochrome"), self->op,
                             self->version(), hk_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(hk_params);
 
  const char *astia_params_input =
  "20f59e427e278d42a2ae6f4218265742c69f4e4282bb1b4200831942eca40942d85cb641000048430000c842083a964214368d42fb258b42928b73424cad4d4231ab3e42093f3c42d38e0c42d828fb412299b841c6e7ad41b2a0a44296dd90422827874224e97c42f4606f425c795b42088b434229b7154206ff1442f61f074229a70442a620fa4120bc9b4160729b41bc109b41ce889441be73904110486e419878b940fa849142fc3c7d42e4d37442aed36f42c5b50d42877d0742e821a0411ae11341a871a4be4a1979c17d9794c18c26ebc17682e8bfec9823c1d2ae6cc03bca04c27ea111c10000000000000000bcda0b3f18478e40040b023f66ca9741097a96413c7eb14104090b41079b0b4236804a423a1624412c95ab41f8e0323f672c684136a909401fb4dc4134380e4188acfe400e6d3e425f60564040228d40b041904176f8dd41127986420bcc2a42b88bc041e7eaa9402ab50341e5f6f841a2dab840333c36426ae64fc106e5aac1a0eac5c19e42babf844ad8c139be78c198f65fc1101fa8bda089444163890b413a7f8a41c748b741979736422c2798413b18fc4024fde6414f3b73410000000000000000fcfb134234fb754246425b4140dc353f4487ce412cf53142ea844d41089ebb41bc42ed411c3d7641af131b41aea35ac0e48351c13f1a92c0b182a7c1892d8ac158c606c2406af6c1992d3ac1dd9ae2c149a950c2c608e7c0c0ff0dc268aaf3c1bf8b90c1aea004c21f564bc2db46c9c0a8a098bf5ee18cc20b3878c18de1d7c1e0c533c142ba1bc1ecd83cc106d411c20603e9c0907a30c0bea4a142fe288c42d48b6042a4c54e42ac414842f68a1542804a1442510b06429c18ac41264845435e58b24213c197428e4b8d4255e18c42ceb17542d0d64042d3293942f92f364293aa0f4296bc0c42b42fb841ceadb441ca69a542e67e984293338742c2248742a8c07c42ee3c6342923a5a429e07184213dc2042d6901f42301d0d42778a2442d6dfd74108a7b541baecc641de56e841bedfb3417a076f41ec9dc24123d19742081185424e427a427c4578424ab81942c07c224200eea94108d1134170d930bfd5e49ac143b4adc1e3180bc2248b4dbf3e6624c13e266bc034f6c6c1f5a3ecc000803bb9008890baf892bf3eb7ffc0400a16fd3f497ab04161009a416eddc941121a0d417b740d42cbf6354235603e4136ce9c41002c493eda48614199e90640ac88f64135230e41a69fac40dbb23c427bce3540a18b4d40f4ce5a41c7b0d84110816b42b4ddf741d01a98418d2510413dcc8b412331bd41efe896407578e64129fd98c1617010c2242005c23e4d85c05be37ac194fa68bf0178d2c028bacc3d46f2674121d83a413a349f416a60d141d6e0264272e8a2417c590f414c1cc241c4df634100e0f63a00b6003c1df73442b2b97442d4d78f41481be73f06bbca41d39c1642f48c674191c5a8414638b9413cc6794191c3354102e024c0262653c11276b8c07a3ad5c1d4d8c1c1e7b039c28ec129c2b5156ec1d82a26c2160a97c2626400c1bec74ac2fe5bf6c1465e87c13ab90dc2c5c47ec2581a2bc038ea0cbf06b38bc2488593c1f8140dc240a6b6c1689254c182c683c13e216cc2a03dd9c0028e10c031000000";
 
  uint8_t *astia_params = dt_exif_xmp_decode(
      astia_params_input, strlen(astia_params_input), &params_len);
 
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(astia_params);
  dt_gui_presets_add_generic(_("Fuji Astia emulation"), self->op,
                             self->version(), astia_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(astia_params);
 
 
  const char *chrome_params_input =
  "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";
 
  uint8_t *chrome_params = dt_exif_xmp_decode(
      chrome_params_input, strlen(chrome_params_input), &params_len);
 
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(chrome_params);
  dt_gui_presets_add_generic(_("Fuji Classic Chrome emulation"), self->op,
                             self->version(), chrome_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(chrome_params);
 
 
  const char *mchrome_params_input =
  "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";
 
  uint8_t *mchrome_params = dt_exif_xmp_decode(
      mchrome_params_input, strlen(mchrome_params_input), &params_len);
 
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(mchrome_params);
  dt_gui_presets_add_generic(_("Fuji Monochrome emulation"), self->op,
                             self->version(), mchrome_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(mchrome_params);
 
 
  const char *provia_params_input =
  "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";
 
  uint8_t *provia_params = dt_exif_xmp_decode(
      provia_params_input, strlen(provia_params_input), &params_len);
 
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(provia_params);
  dt_gui_presets_add_generic(_("Fuji Provia emulation"), self->op,
                             self->version(), provia_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(provia_params);
 
 
  const char *velvia_params_input =
  "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";
 
  uint8_t *velvia_params = dt_exif_xmp_decode(
      velvia_params_input, strlen(velvia_params_input), &params_len);
 
  assert(params_len == sizeof(dt_iop_colorchecker_params_t));
  assert(velvia_params);
  dt_gui_presets_add_generic(_("Fuji Velvia emulation"), self->op,
                             self->version(), velvia_params, params_len, 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_free(velvia_params);
}
 
// fast logarithms stolen from paul mineiro http://fastapprox.googlecode.com/svn/trunk/fastapprox/src/fastonebigheader.h
#if 0//def __SSE2__
#include <xmmintrin.h>
 
typedef __m128 v4sf;
typedef __m128i v4si;
 
#define v4si_to_v4sf _mm_cvtepi32_ps
#define v4sf_to_v4si _mm_cvttps_epi32
 
#define v4sfl(x) ((const v4sf) { (x), (x), (x), (x) })
#define v2dil(x) ((const v4si) { (x), (x) })
#define v4sil(x) v2dil((((unsigned long long) (x)) << 32) | (x))
static inline v4sf
vfastlog2 (v4sf x)
{
  union { v4sf f; v4si i; } vx = { x };
  union { v4si i; v4sf f; } mx; mx.i = (vx.i & v4sil (0x007FFFFF)) | v4sil (0x3f000000);
  v4sf y = v4si_to_v4sf (vx.i);
  y *= v4sfl (1.1920928955078125e-7f);
 
  const v4sf c_124_22551499 = v4sfl (124.22551499f);
  const v4sf c_1_498030302 = v4sfl (1.498030302f);
  const v4sf c_1_725877999 = v4sfl (1.72587999f);
  const v4sf c_0_3520087068 = v4sfl (0.3520887068f);
 
  return y - c_124_22551499
    - c_1_498030302 * mx.f
    - c_1_725877999 / (c_0_3520087068 + mx.f);
}
 
static inline v4sf
vfastlog (v4sf x)
{
  const v4sf c_0_69314718 = v4sfl (0.69314718f);
  return c_0_69314718 * vfastlog2 (x);
}
 
// thinplate spline kernel \phi(r) = 2 r^2 ln(r)
static inline v4sf kerneldist4(const float *x, const float *y)
{
  const float r2 =
      (x[0]-y[0])*(x[0]-y[0])+
      (x[1]-y[1])*(x[1]-y[1])+
      (x[2]-y[2])*(x[2]-y[2]);
  return r2 * fastlog(MAX(1e-8f,r2));
}
#endif
 
// static inline float
// fasterlog(float x)
// {
//   union { float f; uint32_t i; } vx = { x };
//   float y = vx.i;
//   y *= 8.2629582881927490e-8f;
//   return y - 87.989971088f;
// }
 
// thinplate spline kernel \phi(r) = 2 r^2 ln(r)
#if defined(_OPENMP) && defined(OPENMP_SIMD_)
#pragma omp declare simd
#endif
static inline float kernel(const float *x, const float *y)
{
  // return r*r*logf(MAX(1e-8f,r));
  // well damnit, this speedup thing unfortunately shows severe artifacts.
  // return r*r*fasterlog(MAX(1e-8f,r));
  // this one seems to be a lot better, let's see how it goes:
  const float r2 =
      (x[0]-y[0])*(x[0]-y[0])+
      (x[1]-y[1])*(x[1]-y[1])+
      (x[2]-y[2])*(x[2]-y[2]);
  return r2*fastlog(MAX(1e-8f,r2));
}
 
__DT_CLONE_TARGETS__
int process(struct dt_iop_module_t *self, const dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
             void *const ovoid)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  const dt_iop_roi_t *const roi_out = &piece->roi_out;
  const dt_iop_colorchecker_data_t *const data = (dt_iop_colorchecker_data_t *)piece->data;
  const int ch = 4;
  __OMP_PARALLEL_FOR__(collapse(2))
  for(int j=0;j<roi_out->height;j++)
  {
    for(int i=0;i<roi_out->width;i++)
    {
      const float *in = ((float *)ivoid) + (size_t)ch * (j * roi_in->width + i);
      float *out = ((float *)ovoid) + (size_t)ch * (j * roi_in->width + i);
      out[0] = data->coeff_L[data->num_patches];
      out[1] = data->coeff_a[data->num_patches];
      out[2] = data->coeff_b[data->num_patches];
      // polynomial part:
      out[0] += data->coeff_L[data->num_patches+1] * in[0] +
                data->coeff_L[data->num_patches+2] * in[1] +
                data->coeff_L[data->num_patches+3] * in[2];
      out[1] += data->coeff_a[data->num_patches+1] * in[0] +
                data->coeff_a[data->num_patches+2] * in[1] +
                data->coeff_a[data->num_patches+3] * in[2];
      out[2] += data->coeff_b[data->num_patches+1] * in[0] +
                data->coeff_b[data->num_patches+2] * in[1] +
                data->coeff_b[data->num_patches+3] * in[2];
#if defined(_OPENMP) && defined(OPENMP_SIMD_) // <== nice try, i don't think this does anything here
#pragma omp simd
#endif
      for(int k=0;k<data->num_patches;k++)
      { // rbf from thin plate spline
        const float phi = kernel(in, data->source_Lab + 3*k);
        out[0] += data->coeff_L[k] * phi;
        out[1] += data->coeff_a[k] * phi;
        out[2] += data->coeff_b[k] * phi;
      }
    }
  }
  if(pipe->mask_display & DT_DEV_PIXELPIPE_DISPLAY_MASK) dt_iop_alpha_copy(ivoid, ovoid, roi_out->width, roi_out->height);
  return 0;
}
 
 
#ifdef 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_out = &piece->roi_out;
  dt_iop_colorchecker_data_t *d = (dt_iop_colorchecker_data_t *)piece->data;
  dt_iop_colorchecker_global_data_t *gd = (dt_iop_colorchecker_global_data_t *)self->global_data;
 
  const int devid = pipe->devid;
  const int width = roi_out->width;
  const int height = roi_out->height;
  const int num_patches = d->num_patches;
 
  cl_int err = -999;
  cl_mem dev_params = NULL;
 
  const size_t params_size = (size_t)(4 * (2 * num_patches + 4)) * sizeof(float);
  float *params = malloc(params_size);
  float *idx = params;
 
  // re-arrange data->source_Lab and data->coeff_{L,a,b} into float4
  for(int n = 0; n < num_patches; n++, idx += 4)
  {
    idx[0] = d->source_Lab[3 * n];
    idx[1] = d->source_Lab[3 * n + 1];
    idx[2] = d->source_Lab[3 * n + 2];
    idx[3] = 0.0f;
  }
 
  for(int n = 0; n < num_patches + 4; n++, idx += 4)
  {
    idx[0] = d->coeff_L[n];
    idx[1] = d->coeff_a[n];
    idx[2] = d->coeff_b[n];
    idx[3] = 0.0f;
  }
 
  dev_params = dt_opencl_copy_host_to_device_constant(devid, params_size, params);
  if(IS_NULL_PTR(dev_params)) goto error;
 
  size_t sizes[3] = { ROUNDUPDWD(width, devid), ROUNDUPDHT(height, devid), 1 };
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 0, sizeof(cl_mem), (void *)&dev_in);
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 1, sizeof(cl_mem), (void *)&dev_out);
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 2, sizeof(int), (void *)&width);
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 3, sizeof(int), (void *)&height);
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 4, sizeof(int), (void *)&num_patches);
  dt_opencl_set_kernel_arg(devid, gd->kernel_colorchecker, 5, sizeof(cl_mem), (void *)&dev_params);
  err = dt_opencl_enqueue_kernel_2d(devid, gd->kernel_colorchecker, sizes);
  if(err != CL_SUCCESS) goto error;
 
  dt_opencl_release_mem_object(dev_params);
  dt_free(params);
  return TRUE;
 
error:
  dt_free(params);
  dt_opencl_release_mem_object(dev_params);
  dt_print(DT_DEBUG_OPENCL, "[opencl_colorchecker] couldn't enqueue kernel! %d\n", err);
  return FALSE;
}
#endif
 
 
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_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)p1;
  dt_iop_colorchecker_data_t *d = (dt_iop_colorchecker_data_t *)piece->data;
 
  d->num_patches = CLAMP(p->num_patches, 0, MAX_PATCHES);
  const int N = d->num_patches, N4 = N + 4;
  for(int k = 0; k < N; k++)
  {
    d->source_Lab[3*k+0] = p->source_L[k];
    d->source_Lab[3*k+1] = p->source_a[k];
    d->source_Lab[3*k+2] = p->source_b[k];
  }
 
  // initialize coefficients with default values that will be
  // used for N<=4 and if coefficient matrix A is singular
  for(int i=0;i<4+N;i++)
  {
    d->coeff_L[i] = 0;
    d->coeff_a[i] = 0;
    d->coeff_b[i] = 0;
  }
  d->coeff_L[N + 1] = 1;
  d->coeff_a[N + 2] = 1;
  d->coeff_b[N + 3] = 1;
 
  /*
      Following
 
      K. Anjyo, J. P. Lewis, and F. Pighin, "Scattered data
      interpolation for computer graphics," ACM SIGGRAPH 2014 Courses
      on - SIGGRAPH ’14, 2014.
      http://dx.doi.org/10.1145/2614028.2615425
      http://scribblethink.org/Courses/ScatteredInterpolation/scatteredinterpcoursenotes.pdf
 
      construct the system matrix and the vector of function values and
      solve the set of linear equations
 
      / R   P \  / c \   / f \
      |       |  |   | = |   |
      \ P^t 0 /  \ d /   \ 0 /
 
      for the coefficient vector (c d)^t.
 
      By design of the interpolation scheme the interpolation
      coefficients c for radial non-linear basis functions (the kernel)
      must always vanish for N<=4.  For N<4 the (N+4)x(N+4) coefficient
      matrix A is singular, the linear system has non-unique solutions.
      Thus the cases with N<=4 need special treatment, unique solutions
      are found by setting some of the unknown coefficients to zero and
      solving a smaller linear system.
  */
  switch(N)
  {
  case 0:
    break;
  case 1:
    // interpolation via constant function
    d->coeff_L[N + 1] = p->target_L[0] / p->source_L[0];
    d->coeff_a[N + 2] = p->target_a[0] / p->source_a[0];
    d->coeff_b[N + 3] = p->target_b[0] / p->source_b[0];
    break;
  case 2:
    // interpolation via single constant function and the linear
    // function of the corresponding color channel
    {
      double A[2 * 2] = { 1, p->source_L[0],
                          1, p->source_L[1] };
      double b[2] = { p->target_L[0], p->target_L[1] };
      if(!gauss_solve(A, b, 2)) break;
      d->coeff_L[N + 0] = b[0];
      d->coeff_L[N + 1] = b[1];
    }
    {
      double A[2 * 2] = { 1, p->source_a[0],
                          1, p->source_a[1] };
      double b[2] = { p->target_a[0], p->target_a[1] };
      if(!gauss_solve(A, b, 2)) break;
      d->coeff_a[N + 0] = b[0];
      d->coeff_a[N + 2] = b[1];
    }
    {
      double A[2 * 2] = { 1, p->source_b[0],
                          1, p->source_b[1] };
      double b[2] = { p->target_b[0], p->target_b[1] };
      if(!gauss_solve(A, b, 2)) break;
      d->coeff_b[N + 0] = b[0];
      d->coeff_b[N + 3] = b[1];
    }
    break;
  case 3:
    // interpolation via single constant function, the linear function
    // of the corresponding color channel and the linear functions
    // of the other two color channels having both the same weight
    {
      double A[3 * 3] = { 1, p->source_L[0], p->source_a[0] + p->source_b[0],
                          1, p->source_L[1], p->source_a[1] + p->source_b[1],
                          1, p->source_L[2], p->source_a[2] + p->source_b[2] };
      double b[3] = { p->target_L[0], p->target_L[1], p->target_L[2] };
      if(!gauss_solve(A, b, 3)) break;
      d->coeff_L[N + 0] = b[0];
      d->coeff_L[N + 1] = b[1];
      d->coeff_L[N + 2] = b[2];
      d->coeff_L[N + 3] = b[2];
    }
    {
      double A[3 * 3] = { 1, p->source_a[0], p->source_L[0] + p->source_b[0],
                          1, p->source_a[1], p->source_L[1] + p->source_b[1],
                          1, p->source_a[2], p->source_L[2] + p->source_b[2] };
      double b[3] = { p->target_a[0], p->target_a[1], p->target_a[2] };
      if(!gauss_solve(A, b, 3)) break;
      d->coeff_a[N + 0] = b[0];
      d->coeff_a[N + 1] = b[2];
      d->coeff_a[N + 2] = b[1];
      d->coeff_a[N + 3] = b[2];
    }
    {
      double A[3 * 3] = { 1, p->source_b[0], p->source_L[0] + p->source_a[0],
                          1, p->source_b[1], p->source_L[1] + p->source_a[1],
                          1, p->source_b[2], p->source_L[2] + p->source_a[2] };
      double b[3] = { p->target_b[0], p->target_b[1], p->target_b[2] };
      if(!gauss_solve(A, b, 3)) break;
      d->coeff_b[N + 0] = b[0];
      d->coeff_b[N + 1] = b[2];
      d->coeff_b[N + 2] = b[2];
      d->coeff_b[N + 3] = b[1];
    }
    break;
  case 4:
  {
    // interpolation via constant function and 3 linear functions
    double A[4 * 4] = { 1, p->source_L[0], p->source_a[0], p->source_b[0],
                        1, p->source_L[1], p->source_a[1], p->source_b[1],
                        1, p->source_L[2], p->source_a[2], p->source_b[2],
                        1, p->source_L[3], p->source_a[3], p->source_b[3] };
    int pivot[4];
    if(!gauss_make_triangular(A, pivot, 4)) break;
    {
      double b[4] = { p->target_L[0], p->target_L[1], p->target_L[2], p->target_L[3] };
      gauss_solve_triangular(A, pivot, b, 4);
      d->coeff_L[N + 0] = b[0];
      d->coeff_L[N + 1] = b[1];
      d->coeff_L[N + 2] = b[2];
      d->coeff_L[N + 3] = b[3];
    }
    {
      double b[4] = { p->target_a[0], p->target_a[1], p->target_a[2], p->target_a[3] };
      gauss_solve_triangular(A, pivot, b, 4);
      d->coeff_a[N + 0] = b[0];
      d->coeff_a[N + 1] = b[1];
      d->coeff_a[N + 2] = b[2];
      d->coeff_a[N + 3] = b[3];
    }
    {
      double b[4] = { p->target_b[0], p->target_b[1], p->target_b[2], p->target_b[3] };
      gauss_solve_triangular(A, pivot, b, 4);
      d->coeff_b[N + 0] = b[0];
      d->coeff_b[N + 1] = b[1];
      d->coeff_b[N + 2] = b[2];
      d->coeff_b[N + 3] = b[3];
    }
    break;
  }
  default:
  {
    // setup linear system of equations
    double *A = malloc(sizeof(double) * N4 * N4);
    double *b = malloc(sizeof(double) * N4);
    // coefficients from nonlinear radial kernel functions
    for(int j=0;j<N;j++)
      for(int i=j;i<N;i++)
        A[j*N4+i] = A[i*N4+j] = kernel(d->source_Lab+3*i, d->source_Lab+3*j);
    // coefficients from constant and linear functions
    for(int i=0;i<N;i++) A[i*N4+N+0] = A[(N+0)*N4+i] = 1;
    for(int i=0;i<N;i++) A[i*N4+N+1] = A[(N+1)*N4+i] = d->source_Lab[3*i+0];
    for(int i=0;i<N;i++) A[i*N4+N+2] = A[(N+2)*N4+i] = d->source_Lab[3*i+1];
    for(int i=0;i<N;i++) A[i*N4+N+3] = A[(N+3)*N4+i] = d->source_Lab[3*i+2];
    // lower-right zero block
    for(int j=N;j<N4;j++)
      for(int i=N;i<N4;i++)
        A[j*N4+i] = 0;
    // make coefficient matrix triangular
    int *pivot = malloc(sizeof(*pivot) * N4);
    if (gauss_make_triangular(A, pivot, N4))
    {
      // calculate coefficients for L channel
      for(int i=0;i<N;i++) b[i] = p->target_L[i];
      for(int i=N;i<N+4;i++) b[i] = 0;
      gauss_solve_triangular(A, pivot, b, N4);
      for(int i=0;i<N+4;i++) d->coeff_L[i] = b[i];
      // calculate coefficients for a channel
      for(int i=0;i<N;i++) b[i] = p->target_a[i];
      for(int i=N;i<N+4;i++) b[i] = 0;
      gauss_solve_triangular(A, pivot, b, N4);
      for(int i=0;i<N+4;i++) d->coeff_a[i] = b[i];
      // calculate coefficients for b channel
      for(int i=0;i<N;i++) b[i] = p->target_b[i];
      for(int i=N;i<N+4;i++) b[i] = 0;
      gauss_solve_triangular(A, pivot, b, N4);
      for(int i=0;i<N+4;i++) d->coeff_b[i] = b[i];
    }
    // free resources
    dt_free(pivot);
    dt_free(b);
    dt_free(A);
  }
  }
}
 
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_colorchecker_data_t));
  piece->data_size = sizeof(dt_iop_colorchecker_data_t);
}
 
void cleanup_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_free_align(piece->data);
  piece->data = NULL;
}
 
void gui_reset(struct dt_iop_module_t *self)
{
  dt_iop_color_picker_reset(self, TRUE);
}
 
void _colorchecker_rebuild_patch_list(struct dt_iop_module_t *self)
{
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  if(g->patch >= p->num_patches || g->patch < 0) return;
 
  if(dt_bauhaus_combobox_length(g->combobox_patch) != p->num_patches)
  {
    dt_bauhaus_combobox_clear(g->combobox_patch);
    char cboxentry[1024];
    for(int k=0;k<p->num_patches;k++)
    {
      snprintf(cboxentry, sizeof(cboxentry), _("patch #%d"), k);
      dt_bauhaus_combobox_add(g->combobox_patch, cboxentry);
    }
    if(p->num_patches <= 24)
      dtgtk_drawing_area_set_aspect_ratio(g->area, 2.0/3.0);
    else
      dtgtk_drawing_area_set_aspect_ratio(g->area, 1.0);
    // FIXME: why not just use g->patch for everything?
    g->drawn_patch = dt_bauhaus_combobox_get(g->combobox_patch);
  }
}
 
void _colorchecker_update_sliders(struct dt_iop_module_t *self)
{
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  if(g->patch >= p->num_patches || g->patch < 0) return;
 
  if(g->absolute_target)
  {
    dt_bauhaus_slider_set(g->scale_L, p->target_L[g->patch]);
    dt_bauhaus_slider_set(g->scale_a, p->target_a[g->patch]);
    dt_bauhaus_slider_set(g->scale_b, p->target_b[g->patch]);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    dt_bauhaus_slider_set(g->scale_C, Cout);
  }
  else
  {
    dt_bauhaus_slider_set(g->scale_L, p->target_L[g->patch] - p->source_L[g->patch]);
    dt_bauhaus_slider_set(g->scale_a, p->target_a[g->patch] - p->source_a[g->patch]);
    dt_bauhaus_slider_set(g->scale_b, p->target_b[g->patch] - p->source_b[g->patch]);
    const float Cin = sqrtf(
        p->source_a[g->patch]*p->source_a[g->patch] +
        p->source_b[g->patch]*p->source_b[g->patch]);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    dt_bauhaus_slider_set(g->scale_C, Cout-Cin);
  }
}
 
void gui_update(struct dt_iop_module_t *self)
{
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
 
  _colorchecker_rebuild_patch_list(self);
  _colorchecker_update_sliders(self);
 
  gtk_widget_queue_draw(g->area);
}
 
void init(dt_iop_module_t *module)
{
  module->params = calloc(1, sizeof(dt_iop_colorchecker_params_t));
  module->default_params = calloc(1, sizeof(dt_iop_colorchecker_params_t));
  module->default_enabled = 0;
  module->params_size = sizeof(dt_iop_colorchecker_params_t);
  module->gui_data = NULL;
 
  dt_iop_colorchecker_params_t *d = module->default_params;
  d->num_patches = colorchecker_patches;
  for(int k = 0; k < d->num_patches; k++)
  {
    d->source_L[k] = d->target_L[k] = colorchecker_Lab[3*k+0];
    d->source_a[k] = d->target_a[k] = colorchecker_Lab[3*k+1];
    d->source_b[k] = d->target_b[k] = colorchecker_Lab[3*k+2];
  }
}
 
void init_global(dt_iop_module_so_t *module)
{
  dt_iop_colorchecker_global_data_t *gd
      = (dt_iop_colorchecker_global_data_t *)malloc(sizeof(dt_iop_colorchecker_global_data_t));
  module->data = gd;
 
  const int program = 8; // extended.cl, from programs.conf
  gd->kernel_colorchecker = dt_opencl_create_kernel(program, "colorchecker");
}
 
void cleanup_global(dt_iop_module_so_t *module)
{
  dt_iop_colorchecker_global_data_t *gd = (dt_iop_colorchecker_global_data_t *)module->data;
  dt_opencl_free_kernel(gd->kernel_colorchecker);
  dt_free(module->data);
}
 
void color_picker_apply(dt_iop_module_t *self, GtkWidget *picker, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  if(p->num_patches <= 0) return;
 
  // determine patch based on color picker result
  const dt_aligned_pixel_t picked_mean = { self->picked_color[0], self->picked_color[1], self->picked_color[2] };
  int best_patch = 0;
  for(int patch = 1; patch < p->num_patches; patch++)
  {
    const dt_aligned_pixel_t Lab = { p->source_L[patch], p->source_a[patch], p->source_b[patch] };
    if((self->request_color_pick == DT_REQUEST_COLORPICK_MODULE)
       && (sqf(picked_mean[0] - Lab[0])
               + sqf(picked_mean[1] - Lab[1])
               + sqf(picked_mean[2] - Lab[2])
           < sqf(picked_mean[0] - p->source_L[best_patch])
                 + sqf(picked_mean[1] - p->source_a[best_patch])
                 + sqf(picked_mean[2] - p->source_b[best_patch])))
      best_patch = patch;
  }
 
  if(best_patch != g->drawn_patch)
  {
    g->patch = g->drawn_patch = best_patch;
    ++darktable.gui->reset;
    dt_bauhaus_combobox_set(g->combobox_patch, g->drawn_patch);
    _colorchecker_update_sliders(self);
    --darktable.gui->reset;
    gtk_widget_queue_draw(g->area);
  }
}
 
static void target_L_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  if(g->patch >= p->num_patches || g->patch < 0) return;
  if(g->absolute_target)
    p->target_L[g->patch] = dt_bauhaus_slider_get(slider);
  else
    p->target_L[g->patch] = p->source_L[g->patch] + dt_bauhaus_slider_get(slider);
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
 
static void target_a_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  if(g->patch >= p->num_patches || g->patch < 0) return;
  if(g->absolute_target)
  {
    p->target_a[g->patch] = CLAMP(dt_bauhaus_slider_get(slider), -128.0, 128.0);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_C, Cout);
    --darktable.gui->reset;
  }
  else
  {
    p->target_a[g->patch] = CLAMP(p->source_a[g->patch] + dt_bauhaus_slider_get(slider), -128.0, 128.0);
    const float Cin = sqrtf(
        p->source_a[g->patch]*p->source_a[g->patch] +
        p->source_b[g->patch]*p->source_b[g->patch]);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_C, Cout-Cin);
    --darktable.gui->reset;
  }
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
 
static void target_b_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  if(g->patch >= p->num_patches || g->patch < 0) return;
  if(g->absolute_target)
  {
    p->target_b[g->patch] = CLAMP(dt_bauhaus_slider_get(slider), -128.0, 128.0);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_C, Cout);
    --darktable.gui->reset;
  }
  else
  {
    p->target_b[g->patch] = CLAMP(p->source_b[g->patch] + dt_bauhaus_slider_get(slider), -128.0, 128.0);
    const float Cin = sqrtf(
        p->source_a[g->patch]*p->source_a[g->patch] +
        p->source_b[g->patch]*p->source_b[g->patch]);
    const float Cout = sqrtf(
        p->target_a[g->patch]*p->target_a[g->patch]+
        p->target_b[g->patch]*p->target_b[g->patch]);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_C, Cout-Cin);
    --darktable.gui->reset;
  }
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
 
static void target_C_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  if(g->patch >= p->num_patches || g->patch < 0) return;
  const float Cin = sqrtf(
      p->source_a[g->patch]*p->source_a[g->patch] +
      p->source_b[g->patch]*p->source_b[g->patch]);
  const float Cout = MAX(1e-4f, sqrtf(
      p->target_a[g->patch]*p->target_a[g->patch]+
      p->target_b[g->patch]*p->target_b[g->patch]));
 
  if(g->absolute_target)
  {
    const float Cnew = CLAMP(dt_bauhaus_slider_get(slider), 0.01, 128.0);
    p->target_a[g->patch] = CLAMP(p->target_a[g->patch]*Cnew/Cout, -128.0, 128.0);
    p->target_b[g->patch] = CLAMP(p->target_b[g->patch]*Cnew/Cout, -128.0, 128.0);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_a, p->target_a[g->patch]);
    dt_bauhaus_slider_set(g->scale_b, p->target_b[g->patch]);
    --darktable.gui->reset;
  }
  else
  {
    const float Cnew = CLAMP(Cin + dt_bauhaus_slider_get(slider), 0.01, 128.0);
    p->target_a[g->patch] = CLAMP(p->target_a[g->patch]*Cnew/Cout, -128.0, 128.0);
    p->target_b[g->patch] = CLAMP(p->target_b[g->patch]*Cnew/Cout, -128.0, 128.0);
    ++darktable.gui->reset; // avoid history item
    dt_bauhaus_slider_set(g->scale_a, p->target_a[g->patch] - p->source_a[g->patch]);
    dt_bauhaus_slider_set(g->scale_b, p->target_b[g->patch] - p->source_b[g->patch]);
    --darktable.gui->reset;
  }
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
 
static void target_callback(GtkWidget *combo, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  g->absolute_target = dt_bauhaus_combobox_get(combo);
  ++darktable.gui->reset;
  _colorchecker_update_sliders(self);
  --darktable.gui->reset;
  // switch off colour picker, it'll interfere with other changes of the patch:
  dt_iop_color_picker_reset(self, TRUE);
  gtk_widget_queue_draw(g->area);
}
 
static void patch_callback(GtkWidget *combo, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  g->drawn_patch = g->patch = dt_bauhaus_combobox_get(combo);
  ++darktable.gui->reset;
  _colorchecker_update_sliders(self);
  --darktable.gui->reset;
  // switch off colour picker, it'll interfere with other changes of the patch:
  dt_iop_color_picker_reset(self, TRUE);
  gtk_widget_queue_draw(g->area);
}
 
static gboolean checker_draw(GtkWidget *widget, cairo_t *crf, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
 
  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);
  // clear bg
  cairo_set_source_rgb(cr, .2, .2, .2);
  cairo_paint(cr);
 
  cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
  const int cells_x = p->num_patches > 24 ? 7 : 6;
  const int cells_y = p->num_patches > 24 ? 7 : 4;
  for(int j = 0; j < cells_y; j++)
  {
    for(int i = 0; i < cells_x; i++)
    {
      const int patch = i + j*cells_x;
      if(patch >= p->num_patches) continue;
 
      const dt_aligned_pixel_t Lab = { p->source_L[patch], p->source_a[patch], p->source_b[patch] };
      dt_aligned_pixel_t rgb, XYZ;
      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, width * i / (float)cells_x, height * j / (float)cells_y,
          width / (float)cells_x - DT_PIXEL_APPLY_DPI(1),
          height / (float)cells_y - DT_PIXEL_APPLY_DPI(1));
      cairo_fill(cr);
      if(fabsf(p->target_L[patch] - p->source_L[patch]) > 1e-5f ||
         fabsf(p->target_a[patch] - p->source_a[patch]) > 1e-5f ||
         fabsf(p->target_b[patch] - p->source_b[patch]) > 1e-5f)
      {
        cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(2.));
        cairo_set_source_rgb(cr, 0.8, 0.8, 0.8);
        cairo_rectangle(cr,
            width * i / (float)cells_x + DT_PIXEL_APPLY_DPI(1),
            height * j / (float)cells_y + DT_PIXEL_APPLY_DPI(1),
            width / (float)cells_x - DT_PIXEL_APPLY_DPI(3),
            height / (float)cells_y - DT_PIXEL_APPLY_DPI(3));
        cairo_stroke(cr);
        cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.));
        cairo_set_source_rgb(cr, 0.2, 0.2, 0.2);
        cairo_rectangle(cr,
            width * i / (float)cells_x + DT_PIXEL_APPLY_DPI(2),
            height * j / (float)cells_y + DT_PIXEL_APPLY_DPI(2),
            width / (float)cells_x - DT_PIXEL_APPLY_DPI(5),
            height / (float)cells_y - DT_PIXEL_APPLY_DPI(5));
        cairo_stroke(cr);
      }
    }
  }
 
  const int draw_i = g->drawn_patch % cells_x;
  const int draw_j = g->drawn_patch / cells_x;
  float color = 1.0;
  if(p->source_L[g->drawn_patch] > 80) color = 0.0;
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(2.));
  cairo_set_source_rgb(cr, color, color, color);
  cairo_rectangle(cr,
      width * draw_i / (float) cells_x + DT_PIXEL_APPLY_DPI(5),
      height * draw_j / (float) cells_y + DT_PIXEL_APPLY_DPI(5),
      width / (float) cells_x - DT_PIXEL_APPLY_DPI(11),
      height / (float) cells_y - DT_PIXEL_APPLY_DPI(11));
  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 checker_motion_notify(GtkWidget *widget, GdkEventMotion *event,
    gpointer user_data)
{
  // highlight?
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;
  const float mouse_x = CLAMP(event->x, 0, width);
  const float mouse_y = CLAMP(event->y, 0, height);
  int cells_x = 6, cells_y = 4;
  if(p->num_patches > 24)
  {
    cells_x = 7;
    cells_y = 7;
  }
  const float mx = mouse_x * cells_x / (float)width;
  const float my = mouse_y * cells_y / (float)height;
  const int patch = (int)mx + cells_x * (int)my;
  if(patch < 0 || patch >= p->num_patches) return FALSE;
  char tooltip[1024];
  snprintf(tooltip, sizeof(tooltip),
      _("(%2.2f %2.2f %2.2f)\n"
        "altered patches are marked with an outline\n"
        "click to select\n"
        "double-click to reset\n"
        "right click to delete patch\n"
        "shift+click while color picking to replace patch"),
      p->source_L[patch], p->source_a[patch], p->source_b[patch]);
  gtk_widget_set_tooltip_text(g->area, tooltip);
  return TRUE;
}
 
static gboolean checker_button_press(GtkWidget *widget, GdkEventButton *event,
                                                    gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  dt_iop_colorchecker_gui_data_t *g = (dt_iop_colorchecker_gui_data_t *)self->gui_data;
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->params;
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  int width = allocation.width, height = allocation.height;
  const float mouse_x = CLAMP(event->x, 0, width);
  const float mouse_y = CLAMP(event->y, 0, height);
  int cells_x = 6, cells_y = 4;
  if(p->num_patches > 24)
  {
    cells_x = 7;
    cells_y = 7;
  }
  const float mx = mouse_x * cells_x / (float)width;
  const float my = mouse_y * cells_y / (float)height;
  int patch = (int)mx + cells_x*(int)my;
  if(event->button == 1 && event->type == GDK_2BUTTON_PRESS)
  { // reset on double click
    if(patch < 0 || patch >= p->num_patches) return FALSE;
    p->target_L[patch] = p->source_L[patch];
    p->target_a[patch] = p->source_a[patch];
    p->target_b[patch] = p->source_b[patch];
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
    ++darktable.gui->reset;
    _colorchecker_update_sliders(self);
    --darktable.gui->reset;
    gtk_widget_queue_draw(g->area);
    return TRUE;
  }
  else if(event->button == 3 && (patch < p->num_patches))
  {
    // right click: delete patch, move others up
    if(patch < 0 || patch >= p->num_patches) return FALSE;
    memmove(p->target_L+patch, p->target_L+patch+1, sizeof(float)*(p->num_patches-1-patch));
    memmove(p->target_a+patch, p->target_a+patch+1, sizeof(float)*(p->num_patches-1-patch));
    memmove(p->target_b+patch, p->target_b+patch+1, sizeof(float)*(p->num_patches-1-patch));
    memmove(p->source_L+patch, p->source_L+patch+1, sizeof(float)*(p->num_patches-1-patch));
    memmove(p->source_a+patch, p->source_a+patch+1, sizeof(float)*(p->num_patches-1-patch));
    memmove(p->source_b+patch, p->source_b+patch+1, sizeof(float)*(p->num_patches-1-patch));
    p->num_patches--;
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
    ++darktable.gui->reset;
    _colorchecker_rebuild_patch_list(self);
    _colorchecker_update_sliders(self);
    --darktable.gui->reset;
    gtk_widget_queue_draw(g->area);
    return TRUE;
  }
  else if((event->button == 1) &&
          dt_modifier_is(event->state, GDK_SHIFT_MASK) &&
          (self->request_color_pick == DT_REQUEST_COLORPICK_MODULE))
  {
    // shift-left while colour picking: replace source colour
    // if clicked outside the valid patches: add new one
 
    // color channels should be nonzero to avoid numerical issues
    int new_color_valid = fabsf(self->picked_color[0]) > 1.e-3f &&
                          fabsf(self->picked_color[1]) > 1.e-3f &&
                          fabsf(self->picked_color[2]) > 1.e-3f;
    // check if the new color is very close to some color already in the colorchecker
    for(int i=0;i<p->num_patches;++i)
    {
      float color[] = { p->source_L[i], p->source_a[i], p->source_b[i] };
      if(fabsf(self->picked_color[0] - color[0]) < 1.e-3f && fabsf(self->picked_color[1] - color[1]) < 1.e-3f
         && fabsf(self->picked_color[2] - color[2]) < 1.e-3f)
        new_color_valid = FALSE;
    }
    if(new_color_valid)
    {
      if(p->num_patches < 24 && (patch < 0 || patch >= p->num_patches))
      {
        p->num_patches = MIN(MAX_PATCHES, p->num_patches + 1);
        patch = p->num_patches - 1;
      }
      p->target_L[patch] = p->source_L[patch] = self->picked_color[0];
      p->target_a[patch] = p->source_a[patch] = self->picked_color[1];
      p->target_b[patch] = p->source_b[patch] = self->picked_color[2];
      dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
 
      ++darktable.gui->reset;
      _colorchecker_rebuild_patch_list(self);
      dt_bauhaus_combobox_set(g->combobox_patch, patch);
      _colorchecker_update_sliders(self);
      --darktable.gui->reset;
      g->patch = g->drawn_patch = patch;
      gtk_widget_queue_draw(g->area);
    }
    return TRUE;
  }
  if(patch >= p->num_patches) patch = p->num_patches-1;
  dt_bauhaus_combobox_set(g->combobox_patch, patch);
  return FALSE;
}
 
static gboolean checker_leave_notify(GtkWidget *widget, GdkEventCrossing *event,
                                                    gpointer user_data)
{
  return FALSE; // ?
}
 
void gui_init(struct dt_iop_module_t *self)
{
  dt_iop_colorchecker_gui_data_t *g = IOP_GUI_ALLOC(colorchecker);
  dt_iop_colorchecker_params_t *p = (dt_iop_colorchecker_params_t *)self->default_params;
 
  self->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  // custom 24-patch widget in addition to combo box
  g->area = dtgtk_drawing_area_new_with_aspect_ratio(4.0/6.0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->area, TRUE, TRUE, 0);
 
  gtk_widget_add_events(GTK_WIDGET(g->area), GDK_POINTER_MOTION_MASK
                                             | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                             | GDK_LEAVE_NOTIFY_MASK);
  g_signal_connect(G_OBJECT(g->area), "draw", G_CALLBACK(checker_draw), self);
  g_signal_connect(G_OBJECT(g->area), "button-press-event", G_CALLBACK(checker_button_press), self);
  g_signal_connect(G_OBJECT(g->area), "motion-notify-event", G_CALLBACK(checker_motion_notify), self);
  g_signal_connect(G_OBJECT(g->area), "leave-notify-event", G_CALLBACK(checker_leave_notify), self);
 
  g->patch = 0;
  g->drawn_patch = -1;
  g->combobox_patch = dt_bauhaus_combobox_new(darktable.bauhaus, DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->combobox_patch, N_("patch"));
  gtk_widget_set_tooltip_text(g->combobox_patch, _("color checker patch"));
  char cboxentry[1024];
  for(int k=0;k<p->num_patches;k++)
  {
    snprintf(cboxentry, sizeof(cboxentry), _("patch #%d"), k);
    dt_bauhaus_combobox_add(g->combobox_patch, cboxentry);
  }
 
  dt_color_picker_new(self, DT_COLOR_PICKER_POINT_AREA, g->combobox_patch);
 
  g->scale_L = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -100.0, 200.0, 0, 0.0f, 2);
  gtk_widget_set_tooltip_text(g->scale_L, _("adjust target color Lab 'L' channel\nlower values darken target color while higher brighten it"));
  dt_bauhaus_widget_set_label(g->scale_L, N_("lightness"));
 
  g->scale_a = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -256.0, 256.0, 0, 0.0f, 2);
  gtk_widget_set_tooltip_text(g->scale_a, _("adjust target color Lab 'a' channel\nlower values shift target color towards greens while higher shift towards magentas"));
  dt_bauhaus_widget_set_label(g->scale_a, N_("green-magenta offset"));
  dt_bauhaus_slider_set_stop(g->scale_a, 0.0, 0.0, 1.0, 0.2);
  dt_bauhaus_slider_set_stop(g->scale_a, 0.5, 1.0, 1.0, 1.0);
  dt_bauhaus_slider_set_stop(g->scale_a, 1.0, 1.0, 0.0, 0.2);
 
  g->scale_b = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -256.0, 256.0, 0, 0.0f, 2);
  gtk_widget_set_tooltip_text(g->scale_b, _("adjust target color Lab 'b' channel\nlower values shift target color towards blues while higher shift towards yellows"));
  dt_bauhaus_widget_set_label(g->scale_b, N_("blue-yellow offset"));
  dt_bauhaus_slider_set_stop(g->scale_b, 0.0, 0.0, 0.0, 1.0);
  dt_bauhaus_slider_set_stop(g->scale_b, 0.5, 1.0, 1.0, 1.0);
  dt_bauhaus_slider_set_stop(g->scale_b, 1.0, 1.0, 1.0, 0.0);
 
  g->scale_C = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -128.0, 128.0, 0, 0.0f, 2);
  gtk_widget_set_tooltip_text(g->scale_C, _("adjust target color saturation\nadjusts 'a' and 'b' channels of target color in Lab space simultaneously\nlower values scale towards lower saturation while higher scale towards higher saturation"));
  dt_bauhaus_widget_set_label(g->scale_C, N_("saturation"));
 
  g->absolute_target = 0;
  g->combobox_target = dt_bauhaus_combobox_new(darktable.bauhaus, DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->combobox_target, N_("target color"));
  gtk_widget_set_tooltip_text(g->combobox_target, _("control target color of the patches\nrelative - target color is relative from the patch original color\nabsolute - target color is absolute Lab value"));
  dt_bauhaus_combobox_add(g->combobox_target, _("relative"));
  dt_bauhaus_combobox_add(g->combobox_target, _("absolute"));
 
  gtk_box_pack_start(GTK_BOX(self->widget), g->combobox_patch, TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->scale_L, TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->scale_a, TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->scale_b, TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->scale_C, TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), g->combobox_target, TRUE, TRUE, 0);
 
  g_signal_connect(G_OBJECT(g->combobox_patch), "value-changed", G_CALLBACK(patch_callback), self);
  g_signal_connect(G_OBJECT(g->scale_L), "value-changed", G_CALLBACK(target_L_callback), self);
  g_signal_connect(G_OBJECT(g->scale_a), "value-changed", G_CALLBACK(target_a_callback), self);
  g_signal_connect(G_OBJECT(g->scale_b), "value-changed", G_CALLBACK(target_b_callback), self);
  g_signal_connect(G_OBJECT(g->scale_C), "value-changed", G_CALLBACK(target_C_callback), self);
  g_signal_connect(G_OBJECT(g->combobox_target), "value-changed", G_CALLBACK(target_callback), self);
}
 
#undef MAX_PATCHES
 
// 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