channelmixer.c

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/*
  This file is part of darktable,
  Copyright (C) 2010-2011 Bruce Guenter.
  Copyright (C) 2010-2012 Henrik Andersson.
  Copyright (C) 2010-2013, 2016 johannes hanika.
  Copyright (C) 2010 José Carlos García Sogo.
  Copyright (C) 2010 Milan Knížek.
  Copyright (C) 2010 Stuart Henderson.
  Copyright (C) 2011 Antony Dovgal.
  Copyright (C) 2011 Brian Teague.
  Copyright (C) 2011 Olivier Tribout.
  Copyright (C) 2011 Robert Bieber.
  Copyright (C) 2011-2014, 2016, 2019 Tobias Ellinghaus.
  Copyright (C) 2012 Alexandre Prokoudine.
  Copyright (C) 2012 Richard Wonka.
  Copyright (C) 2012, 2014, 2016-2017 Ulrich Pegelow.
  Copyright (C) 2013 hal.
  Copyright (C) 2013-2016 Roman Lebedev.
  Copyright (C) 2013 Simon Spannagel.
  Copyright (C) 2013 Thomas Pryds.
  Copyright (C) 2015 Pedro Côrte-Real.
  Copyright (C) 2017 Heiko Bauke.
  Copyright (C) 2017 Matthieu Moy.
  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 Diederik ter Rahe.
  Copyright (C) 2020 Aldric Renaudin.
  Copyright (C) 2020-2021 Chris Elston.
  Copyright (C) 2020, 2022 Diederik Ter Rahe.
  Copyright (C) 2020 Harold le Clément de Saint-Marcq.
  Copyright (C) 2020-2021 Ralf Brown.
  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/>.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "bauhaus/bauhaus.h"
#include "common/colorspaces.h"
#include "common/debug.h"
#include "common/math.h"
#include "common/opencl.h"
#include "control/control.h"
#include "develop/develop.h"
#include "develop/imageop.h"
#include "develop/imageop_math.h"
#include "develop/openmp_maths.h"
 
#include "gui/gtk.h"
#include "gui/presets.h"
#include "iop/iop_api.h"
 
#include <assert.h>
#include <gtk/gtk.h>
#include <inttypes.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
 
DT_MODULE_INTROSPECTION(2, dt_iop_channelmixer_params_t)
 
typedef enum _channelmixer_output_t
{
  CHANNEL_HUE = 0,
  CHANNEL_SATURATION,
  CHANNEL_LIGHTNESS,
  CHANNEL_RED,
  CHANNEL_GREEN,
  CHANNEL_BLUE,
  CHANNEL_GRAY,
 
  CHANNEL_SIZE
} _channelmixer_output_t;
 
typedef enum _channelmixer_algorithm_t
{
   CHANNEL_MIXER_VERSION_1 = 0,
   CHANNEL_MIXER_VERSION_2 = 1,
} _channelmixer_algorithm_t;
 
typedef struct dt_iop_channelmixer_params_t
{
  float red[CHANNEL_SIZE]; // $MIN: -1.0 $MAX: 1.0
  float green[CHANNEL_SIZE]; // $MIN: -1.0 $MAX: 1.0
  float blue[CHANNEL_SIZE]; // $MIN: -1.0 $MAX: 1.0
  _channelmixer_algorithm_t algorithm_version;
} dt_iop_channelmixer_params_t;
 
typedef struct dt_iop_channelmixer_gui_data_t
{
  GtkBox *vbox;
  GtkWidget *output_channel;                          // Output channel
  GtkWidget *scale_red, *scale_green, *scale_blue;    // red, green, blue
} dt_iop_channelmixer_gui_data_t;
 
typedef enum _channelmixer_operation_mode_t
{
  OPERATION_MODE_RGB = 0,
  OPERATION_MODE_GRAY = 1,
  OPERATION_MODE_HSL_V1 = 2,
  OPERATION_MODE_HSL_V2 = 3,
} _channelmixer_operation_mode_t;
 
typedef struct dt_iop_channelmixer_data_t
{
  float hsl_matrix[9];
  float rgb_matrix[9];
  _channelmixer_operation_mode_t operation_mode;
} dt_iop_channelmixer_data_t;
 
const char *name()
{
  return _("channel mixer");
}
 
const char *deprecated_msg()
{
  return _("this module is deprecated. please use the color calibration module instead.");
}
 
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, display-referred"),
                                      _("linear, RGB"),
                                      _("linear, RGB, display-referred"));
}
 
 
int flags()
{
  return IOP_FLAGS_INCLUDE_IN_STYLES | IOP_FLAGS_SUPPORTS_BLENDING | IOP_FLAGS_ALLOW_TILING | IOP_FLAGS_DEPRECATED;
}
 
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;
}
 
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 == 2)
  {
    typedef struct dt_iop_channelmixer_params_v1_t
    {
      float red[7];
      float green[7];
      float blue[7];
    } dt_iop_channelmixer_params_v1_t;
 
    const dt_iop_channelmixer_params_v1_t *old = (dt_iop_channelmixer_params_v1_t *)old_params;
    dt_iop_channelmixer_params_t *new = (dt_iop_channelmixer_params_t *)new_params;
    dt_iop_channelmixer_params_t *defaults = (dt_iop_channelmixer_params_t *)self->default_params;
 
    *new = *defaults; // start with a fresh copy of default parameters
    new->algorithm_version = CHANNEL_MIXER_VERSION_1;
 
    // copy gray mixing parameters
    new->red[CHANNEL_GRAY] = old->red[6];
    new->green[CHANNEL_GRAY] = old->green[6];
    new->blue[CHANNEL_GRAY] = old->blue[6];
 
    // version 1 does not use RGB mixing when gray is enabled
    if(new->red[CHANNEL_GRAY] == 0.0f && new->green[CHANNEL_GRAY] == 0.0f && new->blue[CHANNEL_GRAY] == 0.0f)
    {
      for(int i = 0; i < 3; i++)
      {
        new->red[CHANNEL_RED + i] = old->red[3 + i];
        new->green[CHANNEL_RED + i] = old->green[3 + i];
        new->blue[CHANNEL_RED + i] = old->blue[3 + i];
      }
    }
 
    // copy HSL mixing parameters
    for(int i = 0; i < 3; i++)
    {
      new->red[i] = old->red[i];
      new->green[i] = old->green[i];
      new->blue[i] = old->blue[i];
    }
    return 0;
  }
  return 1;
}
 
__DT_CLONE_TARGETS__
static void process_hsl_v1(const dt_dev_pixelpipe_iop_t *piece, const float *const restrict in,
                           float *const restrict out, const dt_iop_roi_t *const roi_out)
{
  const dt_iop_channelmixer_data_t *data = (dt_iop_channelmixer_data_t *)piece->data;
  const float *const restrict hsl_matrix = data->hsl_matrix;
  const float *const restrict rgb_matrix = data->rgb_matrix;
  const int ch = piece->dsc_in.channels;
  const size_t pixel_count = (size_t)ch * roi_out->width * roi_out->height;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < pixel_count; k += ch)
  {
    float h, s, l, hmix, smix, lmix;
    dt_aligned_pixel_t rgb;
 
    // Calculate the HSL mix
    hmix = clamp_simd(in[k + 0] * hsl_matrix[0]) + (in[k + 1] * hsl_matrix[1]) + (in[k + 2] * hsl_matrix[2]);
    smix = clamp_simd(in[k + 0] * hsl_matrix[3]) + (in[k + 1] * hsl_matrix[4]) + (in[k + 2] * hsl_matrix[5]);
    lmix = clamp_simd(in[k + 0] * hsl_matrix[6]) + (in[k + 1] * hsl_matrix[7]) + (in[k + 2] * hsl_matrix[8]);
 
    // If HSL mix is used apply to out[]
    if(hmix != 0.0f || smix != 0.0f || lmix != 0.0f)
    {
      // mix into HSL output channels
      rgb2hsl(&(in[k]), &h, &s, &l);
      h = (hmix != 0.0f) ? hmix : h;
      s = (smix != 0.0f) ? smix : s;
      l = (lmix != 0.0f) ? lmix : l;
      hsl2rgb(rgb, h, s, l);
    }
    else // no HSL copy in[] to out[]
    {
      for_each_channel(c,aligned(rgb,in)) rgb[c] = in[k + c];
    }
 
    // Calculate RGB mix
    for(int i = 0, j = 0; i < 3; i++, j += 3)
    {
      out[k + i] = clamp_simd(rgb_matrix[j + 0] * rgb[0]
                              + rgb_matrix[j + 1] * rgb[1]
                              + rgb_matrix[j + 2] * rgb[2]);
    }
  }
}
 
__DT_CLONE_TARGETS__
static void process_hsl_v2(const dt_dev_pixelpipe_iop_t *piece, const float *const restrict in,
                           float *const restrict out, const dt_iop_roi_t *const roi_out)
{
  const dt_iop_channelmixer_data_t *data = (dt_iop_channelmixer_data_t *)piece->data;
  const float *const restrict hsl_matrix = data->hsl_matrix;
  const float *const restrict rgb_matrix = data->rgb_matrix;
  const int ch = piece->dsc_in.channels;
  const size_t pixel_count = (size_t)ch * roi_out->width * roi_out->height;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < pixel_count; k += ch)
  {
    dt_aligned_pixel_t rgb = { in[k], in[k + 1], in[k + 2] };
 
    dt_aligned_pixel_t hsl_mix;
    for(int i = 0, j = 0; i < 3; i++, j += 3)
    {
      hsl_mix[i] = clamp_simd(hsl_matrix[j + 0] * rgb[0]
                               + hsl_matrix[j + 1] * rgb[1]
                               + hsl_matrix[j + 2] * rgb[2]);
    }
 
    // If HSL mix is used apply to out[]
    if(hsl_mix[0] != 0.0 || hsl_mix[1] != 0.0 || hsl_mix[2] != 0.0)
    {
      dt_aligned_pixel_t hsl;
      // rgb2hsl expects all values to be clipped
      for_each_channel(c)
      {
        rgb[c] = clamp_simd(rgb[c]);
      }
      // mix into HSL output channels
      rgb2hsl(rgb, &hsl[0], &hsl[1], &hsl[2]);
      for(int i = 0; i < 3; i++)
      {
        hsl[i] = (hsl_mix[i] != 0.0f) ? hsl_mix[i] : hsl[i];
      }
      hsl2rgb(rgb, hsl[0], hsl[1], hsl[2]);
    }
 
    // Calculate RGB mix
    for(int i = 0, j = 0; i < 3; i++, j += 3)
    {
      out[k + i] = fmaxf(rgb_matrix[j + 0] * rgb[0]
                         + rgb_matrix[j + 1] * rgb[1]
                         + rgb_matrix[j + 2] * rgb[2], 0.0f);
    }
  }
}
 
__DT_CLONE_TARGETS__
static void process_rgb(const dt_dev_pixelpipe_iop_t *piece, const float *const restrict in,
                        float *const restrict out, const dt_iop_roi_t *const roi_out)
{
  const dt_iop_channelmixer_data_t *data = (dt_iop_channelmixer_data_t *)piece->data;
  const float *const restrict rgb_matrix = data->rgb_matrix;
  const int ch = piece->dsc_in.channels;
  const size_t pixel_count = (size_t)ch * roi_out->width * roi_out->height;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < pixel_count; k += ch)
  {
    for(int i = 0, j = 0; i < 3; i++, j += 3)
    {
      out[k + i] = fmaxf(rgb_matrix[j + 0] * in[k + 0]
                         + rgb_matrix[j + 1] * in[k + 1]
                         + rgb_matrix[j + 2] * in[k + 2], 0.0f);
    }
  }
}
 
__DT_CLONE_TARGETS__
static void process_gray(const dt_dev_pixelpipe_iop_t *piece, const float *const restrict in,
                         float *const restrict out, const dt_iop_roi_t *const roi_out)
{
  const dt_iop_channelmixer_data_t *data = (dt_iop_channelmixer_data_t *)piece->data;
  const float *const restrict rgb_matrix = data->rgb_matrix;
  const int ch = piece->dsc_in.channels;
  const size_t pixel_count = (size_t)ch * roi_out->width * roi_out->height;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < pixel_count; k += ch)
  {
    float gray = fmaxf(rgb_matrix[0] * in[k + 0]
                       + rgb_matrix[1] * in[k + 1]
                       + rgb_matrix[2] * in[k + 2], 0.0f);
    out[k + 0] = gray;
    out[k + 1] = gray;
    out[k + 2] = gray;
  }
}
 
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_out = &piece->roi_out;
  const dt_iop_channelmixer_data_t *data = (dt_iop_channelmixer_data_t *)piece->data;
  switch (data->operation_mode)
  {
    case OPERATION_MODE_RGB:
      process_rgb(piece, (const float *const restrict)ivoid, (float *const restrict)ovoid, roi_out);
      break;
    case OPERATION_MODE_GRAY:
      process_gray(piece, (const float *const restrict)ivoid, (float *const restrict)ovoid, roi_out);
      break;
    case OPERATION_MODE_HSL_V1:
      process_hsl_v1(piece, (const float *const restrict)ivoid, (float *const restrict)ovoid, roi_out);
      break;
    case OPERATION_MODE_HSL_V2:
      process_hsl_v2(piece, (const float *const restrict)ivoid, (float *const restrict)ovoid, roi_out);
      break;
    default:
      break;
  }
  if(pipe->mask_display & DT_DEV_PIXELPIPE_DISPLAY_MASK) dt_iop_alpha_copy(ivoid, ovoid, roi_out->width, roi_out->height);
  return 0;
}
 
static void red_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(darktable.gui->reset) return;
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->params;
  dt_iop_channelmixer_gui_data_t *g = (dt_iop_channelmixer_gui_data_t *)self->gui_data;
  const int output_channel_index = dt_bauhaus_combobox_get(g->output_channel);
  const float value = dt_bauhaus_slider_get(slider);
  if(output_channel_index >= 0 && value != p->red[output_channel_index])
  {
    p->red[output_channel_index] = value;
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
  }
}
 
static void green_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(darktable.gui->reset) return;
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->params;
  dt_iop_channelmixer_gui_data_t *g = (dt_iop_channelmixer_gui_data_t *)self->gui_data;
  const int output_channel_index = dt_bauhaus_combobox_get(g->output_channel);
  const float value = dt_bauhaus_slider_get(slider);
  if(output_channel_index >= 0 && value != p->green[output_channel_index])
  {
    p->green[output_channel_index] = value;
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
  }
}
 
static void blue_callback(GtkWidget *slider, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(darktable.gui->reset) return;
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->params;
  dt_iop_channelmixer_gui_data_t *g = (dt_iop_channelmixer_gui_data_t *)self->gui_data;
  const int output_channel_index = dt_bauhaus_combobox_get(g->output_channel);
  const float value = dt_bauhaus_slider_get(slider);
  if(output_channel_index >= 0 && value != p->blue[output_channel_index])
  {
    p->blue[output_channel_index] = value;
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
  }
}
 
static void output_callback(GtkComboBox *combo, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(darktable.gui->reset) return;
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->params;
  dt_iop_channelmixer_gui_data_t *g = (dt_iop_channelmixer_gui_data_t *)self->gui_data;
 
  const int output_channel_index = dt_bauhaus_combobox_get(g->output_channel);
  if(output_channel_index >= 0)
  {
    dt_bauhaus_slider_set(g->scale_red, p->red[output_channel_index]);
    dt_bauhaus_slider_set_default(g->scale_red, output_channel_index == CHANNEL_RED ? 1.0 : 0.0);
    dt_bauhaus_slider_set(g->scale_green, p->green[output_channel_index]);
    dt_bauhaus_slider_set_default(g->scale_green, output_channel_index == CHANNEL_GREEN ? 1.0 : 0.0);
    dt_bauhaus_slider_set(g->scale_blue, p->blue[output_channel_index]);
    dt_bauhaus_slider_set_default(g->scale_blue, output_channel_index == CHANNEL_BLUE ? 1.0 : 0.0);
  }
}
 
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_params_t *p = (dt_iop_channelmixer_params_t *)p1;
  dt_iop_channelmixer_data_t *d = (dt_iop_channelmixer_data_t *)piece->data;
 
  // HSL mixer matrix
  gboolean hsl_mix_mode = FALSE;
  for(int i = CHANNEL_HUE, k = 0; i <= CHANNEL_LIGHTNESS; i++, k += 3)
  {
    d->hsl_matrix[k + 0] = p->red[i];
    d->hsl_matrix[k + 1] = p->green[i];
    d->hsl_matrix[k + 2] = p->blue[i];
    hsl_mix_mode |= p->red[i] != 0.0f || p->green[i] != 0.0f || p->blue[i] != 0.0f;
  }
 
  // RGB mixer matrix
  for(int i = CHANNEL_RED, k = 0; i <= CHANNEL_BLUE; i++, k += 3)
  {
    d->rgb_matrix[k + 0] = p->red[i];
    d->rgb_matrix[k + 1] = p->green[i];
    d->rgb_matrix[k + 2] = p->blue[i];
  }
 
  // Gray
  dt_aligned_pixel_t graymix = { p->red[CHANNEL_GRAY], p->green[CHANNEL_GRAY], p->blue[CHANNEL_GRAY] };
  const gboolean gray_mix_mode = (graymix[0] != 0.0f || graymix[1] != 0.0f || graymix[2] != 0.0f) ? TRUE : FALSE;
 
  // Recompute the 3x3 RGB matrix
  if(gray_mix_mode)
  {
    dt_aligned_pixel_t mixed_gray;
    for(int i = 0; i < 3; i++)
    {
      mixed_gray[i] = (graymix[0] * d->rgb_matrix[i]
                       + graymix[1] * d->rgb_matrix[i + 3]
                       + graymix[2] * d->rgb_matrix[i + 6]);
    }
    for(int i = 0; i < 9; i += 3)
    {
      for(int j = 0; j < 3; j++)
      {
        d->rgb_matrix[i + j] = mixed_gray[j];
      }
    }
  }
 
  if(p->algorithm_version == CHANNEL_MIXER_VERSION_1)
  {
    d->operation_mode = OPERATION_MODE_HSL_V1;
  }
  else if(hsl_mix_mode)
  {
    d->operation_mode = OPERATION_MODE_HSL_V2;
  }
  else if(gray_mix_mode)
  {
    d->operation_mode = OPERATION_MODE_GRAY;
  }
  else
  {
    d->operation_mode = OPERATION_MODE_RGB;
  }
}
 
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_data_t));
  piece->data_size = sizeof(dt_iop_channelmixer_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_update(struct dt_iop_module_t *self)
{
  dt_iop_channelmixer_gui_data_t *g = (dt_iop_channelmixer_gui_data_t *)self->gui_data;
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->params;
 
  const int output_channel_index = dt_bauhaus_combobox_get(g->output_channel);
  if(output_channel_index >= 0)
  {
    dt_bauhaus_slider_set(g->scale_red, p->red[output_channel_index]);
    dt_bauhaus_slider_set(g->scale_green, p->green[output_channel_index]);
    dt_bauhaus_slider_set(g->scale_blue, p->blue[output_channel_index]);
  }
}
 
void init(dt_iop_module_t *module)
{
  dt_iop_default_init(module);
 
  dt_iop_channelmixer_params_t *d = module->default_params;
 
  d->algorithm_version = CHANNEL_MIXER_VERSION_2;
  d->red[CHANNEL_RED] = d->green[CHANNEL_GREEN] = d->blue[CHANNEL_BLUE] = 1.0;
}
 
void gui_init(struct dt_iop_module_t *self)
{
  dt_iop_channelmixer_gui_data_t *g = IOP_GUI_ALLOC(channelmixer);
  dt_iop_channelmixer_params_t *p = (dt_iop_channelmixer_params_t *)self->default_params;
 
  self->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  /* output */
  g->output_channel = dt_bauhaus_combobox_new(darktable.bauhaus, DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(g->output_channel, N_("destination"));
  dt_bauhaus_combobox_add(g->output_channel, _("hue"));
  dt_bauhaus_combobox_add(g->output_channel, _("saturation"));
  dt_bauhaus_combobox_add(g->output_channel, _("lightness"));
  dt_bauhaus_combobox_add(g->output_channel, _("red"));
  dt_bauhaus_combobox_add(g->output_channel, _("green"));
  dt_bauhaus_combobox_add(g->output_channel, _("blue"));
  dt_bauhaus_combobox_add(g->output_channel, C_("channelmixer", "gray"));
  dt_bauhaus_combobox_set(g->output_channel, CHANNEL_RED);
  g_signal_connect(G_OBJECT(g->output_channel), "value-changed", G_CALLBACK(output_callback), self);
 
  /* red */
  g->scale_red = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -2.0, 2.0, 0, p->red[CHANNEL_RED], 3);
  gtk_widget_set_tooltip_text(g->scale_red, _("amount of red channel in the output channel"));
  dt_bauhaus_widget_set_label(g->scale_red, N_("red"));
  g_signal_connect(G_OBJECT(g->scale_red), "value-changed", G_CALLBACK(red_callback), self);
 
  /* green */
  g->scale_green = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -2.0, 2.0, 0, p->green[CHANNEL_RED], 3);
  gtk_widget_set_tooltip_text(g->scale_green, _("amount of green channel in the output channel"));
  dt_bauhaus_widget_set_label(g->scale_green, N_("green"));
  g_signal_connect(G_OBJECT(g->scale_green), "value-changed", G_CALLBACK(green_callback), self);
 
  /* blue */
  g->scale_blue = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(self), -2.0, 2.0, 0, p->blue[CHANNEL_RED], 3);
  gtk_widget_set_tooltip_text(g->scale_blue, _("amount of blue channel in the output channel"));
  dt_bauhaus_widget_set_label(g->scale_blue, N_("blue"));
  g_signal_connect(G_OBJECT(g->scale_blue), "value-changed", G_CALLBACK(blue_callback), self);
 
 
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(g->output_channel), TRUE, TRUE, 0);
 
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(g->scale_red), TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(g->scale_green), TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(g->scale_blue), TRUE, TRUE, 0);
}
 
void init_presets(dt_iop_module_so_t *self)
{
  dt_database_start_transaction(darktable.db);
 
  dt_gui_presets_add_generic(_("swap R and B"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 0, 0, 1, 0 },
                                                              { 0, 0, 0, 0, 1, 0, 0 },
                                                              { 0, 0, 0, 1, 0, 0, 0 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("swap G and B"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0 },
                                                              { 0, 0, 0, 0, 0, 1, 0 },
                                                              { 0, 0, 0, 0, 1, 0, 0 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("color contrast boost"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0.8, 1, 0, 0, 0 },
                                                              { 0, 0, 0.1, 0, 1, 0, 0 },
                                                              { 0, 0, 0.1, 0, 0, 1, 0 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("color details boost"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0.1, 1, 0, 0, 0 },
                                                              { 0, 0, 0.8, 0, 1, 0, 0 },
                                                              { 0, 0, 0.1, 0, 0, 1, 0 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("color artifacts boost"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0.1, 1, 0, 0, 0 },
                                                              { 0, 0, 0.1, 0, 1, 0, 0 },
                                                              { 0, 0, 0.8, 0, 0, 1, 0 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("B/W luminance-based"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.21 },
                                                              { 0, 0, 0, 0, 1, 0, 0.72 },
                                                              { 0, 0, 0, 0, 0, 1, 0.07 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("B/W artifacts boost"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, -0.275 },
                                                              { 0, 0, 0, 0, 1, 0, -0.275 },
                                                              { 0, 0, 0, 0, 0, 1, 1.275 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("B/W smooth skin"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 1.0 },
                                                              { 0, 0, 0, 0, 1, 0, 0.325 },
                                                              { 0, 0, 0, 0, 0, 1, -0.4 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
  dt_gui_presets_add_generic(_("B/W blue artifacts reduce"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.4 },
                                                              { 0, 0, 0, 0, 1, 0, 0.750 },
                                                              { 0, 0, 0, 0, 0, 1, -0.15 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Ilford Delta 100-400"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.21 },
                                                              { 0, 0, 0, 0, 1, 0, 0.42 },
                                                              { 0, 0, 0, 0, 0, 1, 0.37 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Ilford Delta 3200"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.31 },
                                                              { 0, 0, 0, 0, 1, 0, 0.36 },
                                                              { 0, 0, 0, 0, 0, 1, 0.33 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Ilford FP4"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.28 },
                                                              { 0, 0, 0, 0, 1, 0, 0.41 },
                                                              { 0, 0, 0, 0, 0, 1, 0.31 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Ilford HP5"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.23 },
                                                              { 0, 0, 0, 0, 1, 0, 0.37 },
                                                              { 0, 0, 0, 0, 0, 1, 0.40 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Ilford SFX"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.36 },
                                                              { 0, 0, 0, 0, 1, 0, 0.31 },
                                                              { 0, 0, 0, 0, 0, 1, 0.33 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Kodak T-Max 100"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.24 },
                                                              { 0, 0, 0, 0, 1, 0, 0.37 },
                                                              { 0, 0, 0, 0, 0, 1, 0.39 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Kodak T-max 400"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.27 },
                                                              { 0, 0, 0, 0, 1, 0, 0.36 },
                                                              { 0, 0, 0, 0, 0, 1, 0.37 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_gui_presets_add_generic(_("B/W Kodak Tri-X 400"), self->op, self->version(),
                             &(dt_iop_channelmixer_params_t){ { 0, 0, 0, 1, 0, 0, 0.25 },
                                                              { 0, 0, 0, 0, 1, 0, 0.35 },
                                                              { 0, 0, 0, 0, 0, 1, 0.40 },
                                                              CHANNEL_MIXER_VERSION_2 },
                             sizeof(dt_iop_channelmixer_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
 
  dt_database_release_transaction(darktable.db);
}
 
// 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