profile_gamma.c

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/*
   This file is part of darktable,
   Copyright (C) 2009-2013, 2016 johannes hanika.
   Copyright (C) 2010 Alexandre Prokoudine.
   Copyright (C) 2010 Bruce Guenter.
   Copyright (C) 2010-2011 Henrik Andersson.
   Copyright (C) 2010 José Carlos García Sogo.
   Copyright (C) 2010 Pascal de Bruijn.
   Copyright (C) 2011 Jérémy Rosen.
   Copyright (C) 2011 Olivier Tribout.
   Copyright (C) 2011 Robert Bieber.
   Copyright (C) 2011-2014, 2016, 2019 Tobias Ellinghaus.
   Copyright (C) 2012 Richard Wonka.
   Copyright (C) 2013, 2020 Aldric Renaudin.
   Copyright (C) 2014-2016 Roman Lebedev.
   Copyright (C) 2014, 2016-2017 Ulrich Pegelow.
   Copyright (C) 2015 Pedro Côrte-Real.
   Copyright (C) 2017 Heiko Bauke.
   Copyright (C) 2018-2020, 2023, 2025-2026 Aurélien PIERRE.
   Copyright (C) 2018-2019 Edgardo Hoszowski.
   Copyright (C) 2018 Matthieu Moy.
   Copyright (C) 2018 Maurizio Paglia.
   Copyright (C) 2018-2022 Pascal Obry.
   Copyright (C) 2018 rawfiner.
   Copyright (C) 2019 Andreas Schneider.
   Copyright (C) 2019-2020, 2022 Diederik Ter Rahe.
   Copyright (C) 2019 Diederik ter Rahe.
   Copyright (C) 2020-2021 Chris Elston.
   Copyright (C) 2020 Ralf Brown.
   Copyright (C) 2021 Dan Torop.
   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 "widgets/bauhaus.h"
#include "system/openmp.h"
#include "system/target_clones.h"
#include "system/mem_alloc.h"
#include "common/module_versioning.h"
#include "math/math.h"
#include "develop/develop.h"
#include "develop/imageop_math.h"
#include "develop/imageop_gui.h"
 
#include "gui/presets.h"
#include "gui/color_picker_proxy.h"
#include "iop/iop_api.h"
#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "widgets/label.h"
 
DT_MODULE_INTROSPECTION(2, dt_iop_profilegamma_params_t)
 
typedef enum dt_iop_profilegamma_mode_t
{
  PROFILEGAMMA_LOG = 0,  // $DESCRIPTION: "logarithmic"
  PROFILEGAMMA_GAMMA = 1 // $DESCRIPTION: "gamma"
} dt_iop_profilegamma_mode_t;
 
typedef struct dt_iop_profilegamma_params_t
{
  dt_iop_profilegamma_mode_t mode; // $DEFAULT: PROFILEGAMMA_LOG
  float linear;          // $MIN: 0.0 $MAX: 1.0 $DEFAULT: 0.1
  float gamma;           // $MIN: 0.0 $MAX: 1.0 $DEFAULT: 0.45
  float dynamic_range;   // $MIN: 0.01 $MAX: 32.0 $DEFAULT: 10.0 $DESCRIPTION: "dynamic range"
  float grey_point;      // $MIN: 0.1 $MAX: 100.0 $DEFAULT: 18.0 $DESCRIPTION: "middle gray luma"
  float shadows_range;   // $MIN: -16.0 $MAX: 16.0 $DEFAULT: -5.0 $DESCRIPTION: "black relative exposure"
  float security_factor; // $MIN: -100.0 $MAX: 100.0 $DEFAULT: 0.0 $DESCRIPTION: "safety factor"
} dt_iop_profilegamma_params_t;
 
typedef struct dt_iop_profilegamma_gui_data_t
{
  GtkWidget *mode;
  GtkWidget *mode_stack;
  GtkWidget *linear;
  GtkWidget *gamma;
  GtkWidget *dynamic_range;
  GtkWidget *grey_point;
  GtkWidget *shadows_range;
  GtkWidget *security_factor;
  GtkWidget *auto_button;
} dt_iop_profilegamma_gui_data_t;
 
typedef struct dt_iop_profilegamma_data_t
{
  dt_iop_profilegamma_mode_t mode;
  float linear;
  float gamma;
  float table[0x10000];      // precomputed look-up table
  float unbounded_coeffs[3]; // approximation for extrapolation of curve
  float dynamic_range;
  float grey_point;
  float shadows_range;
  float security_factor;
} dt_iop_profilegamma_data_t;
 
const char *name()
{
  return _("unbreak input profile");
}
 
const char **description(struct dt_iop_module_t *self)
{
  return dt_iop_set_description(self, _("correct input color profiles meant to be applied on non-linear RGB"),
                                      _("corrective"),
                                      _("linear, RGB, display-referred"),
                                      _("non-linear, RGB"),
                                      _("non-linear, RGB, display-referred"));
}
 
int default_group()
{
  return IOP_GROUP_TECHNICAL;
}
 
int flags()
{
  return IOP_FLAGS_ONE_INSTANCE | IOP_FLAGS_ALLOW_TILING | IOP_FLAGS_INCLUDE_IN_STYLES
         | IOP_FLAGS_SUPPORTS_BLENDING;
}
 
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 init_presets(dt_iop_module_so_t *self)
{
  dt_iop_profilegamma_params_t p;
  memset(&p, 0, sizeof(p));
 
  p.mode = PROFILEGAMMA_LOG;
  p.grey_point = 18.00f;
  p.security_factor = 0.0f;
 
  // 16 EV preset
  p.dynamic_range = 16.0f;
  p.shadows_range = -12.0f;
  dt_gui_presets_add_generic(_("16 EV dynamic range (generic)"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // 14 EV preset
  p.dynamic_range = 14.0f;
  p.shadows_range = -10.50f;
  dt_gui_presets_add_generic(_("14 EV dynamic range (generic)"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // 12 EV preset
  p.dynamic_range = 12.0f;
  p.shadows_range = -9.0f;
  dt_gui_presets_add_generic(_("12 EV dynamic range (generic)"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // 10 EV preset
  p.dynamic_range = 10.0f;
  p.shadows_range = -7.50f;
  dt_gui_presets_add_generic(_("10 EV dynamic range (generic)"), self->op,
                             self->version(), &p, sizeof(p), 1);
 
  // 08 EV preset
  p.dynamic_range = 8.0f;
  p.shadows_range = -6.0f;
  dt_gui_presets_add_generic(_("08 EV dynamic range (generic)"), self->op,
                             self->version(), &p, sizeof(p), 1);
}
 
 
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_profilegamma_params_v1_t
    {
      float linear;
      float gamma;
    } dt_iop_profilegamma_params_v1_t;
 
    dt_iop_profilegamma_params_v1_t *o = (dt_iop_profilegamma_params_v1_t *)old_params;
    dt_iop_profilegamma_params_t *n = (dt_iop_profilegamma_params_t *)new_params;
    dt_iop_profilegamma_params_t *d = (dt_iop_profilegamma_params_t *)self->default_params;
 
    *n = *d; // start with a fresh copy of default parameters
 
    n->linear = o->linear;
    n->gamma = o->gamma;
    n->mode = PROFILEGAMMA_GAMMA;
    return 0;
  }
  return 1;
}
 
__DT_CLONE_TARGETS__
int process(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;
  dt_iop_profilegamma_data_t *data = (dt_iop_profilegamma_data_t *)piece->data;
 
  const int ch = piece->dsc_in.channels;
 
  switch(data->mode)
  {
    case PROFILEGAMMA_LOG:
    {
      const float grey = data->grey_point / 100.0f;
 
      const float noise = powf(2.0f, -16.0f);
      __OMP_FOR_SIMD__()
      for(size_t k = 0; k < (size_t)ch * roi_out->width * roi_out->height; k++)
      {
        float tmp = ((const float *)ivoid)[k] / grey;
        if (tmp < noise) tmp = noise;
        tmp = (fastlog2(tmp) - data->shadows_range) / (data->dynamic_range);
 
        if (tmp < noise)
        {
          ((float *)ovoid)[k] = noise;
        }
        else
        {
          ((float *)ovoid)[k] = tmp;
        }
      }
      break;
    }
 
    case PROFILEGAMMA_GAMMA:
    {
      __OMP_PARALLEL_FOR__()
      for(int k = 0; k < roi_out->height; k++)
      {
        const float *in = ((float *)ivoid) + (size_t)ch * k * roi_out->width;
        float *out = ((float *)ovoid) + (size_t)ch * k * roi_out->width;
 
        for(int j = 0; j < roi_out->width; j++, in += ch, out += ch)
        {
          for(int i = 0; i < 3; i++)
          {
            // use base curve for values < 1, else use extrapolation.
            if(in[i] < 1.0f)
              out[i] = data->table[CLAMP((int)(in[i] * 0x10000ul), 0, 0xffff)];
            else
              out[i] = dt_iop_eval_exp(data->unbounded_coeffs, in[i]);
          }
        }
      }
      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 apply_auto_grey(dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)self->params;
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
 
  float grey = fmax(fmax(self->picked_color[0], self->picked_color[1]), self->picked_color[2]);
  p->grey_point = 100.f * grey;
 
  dt_gui_freeze_begin();
  dt_bauhaus_slider_set(g->grey_point, p->grey_point);
  dt_gui_freeze_end();
 
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void apply_auto_black(dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)self->params;
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
 
  float noise = powf(2.0f, -16.0f);
 
  // Black
  float black = fmax(fmax(self->picked_color_min[0], self->picked_color_min[1]), self->picked_color_min[2]);
  float EVmin = Log2Thres(black / (p->grey_point / 100.0f), noise);
  EVmin *= (1.0f + p->security_factor / 100.0f);
 
  p->shadows_range = EVmin;
 
  dt_gui_freeze_begin();
  dt_bauhaus_slider_set(g->shadows_range, p->shadows_range);
  dt_gui_freeze_end();
 
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void apply_auto_dynamic_range(dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)self->params;
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
 
  float noise = powf(2.0f, -16.0f);
 
  // Black
  float EVmin = p->shadows_range;
 
  // White
  float white = fmax(fmax(self->picked_color_max[0], self->picked_color_max[1]), self->picked_color_max[2]);
  float EVmax = Log2Thres(white / (p->grey_point / 100.0f), noise);
  EVmax *= (1.0f + p->security_factor / 100.0f);
 
  p->dynamic_range = EVmax - EVmin;
 
  dt_gui_freeze_begin();
  dt_bauhaus_slider_set(g->dynamic_range, p->dynamic_range);
  dt_gui_freeze_end();
 
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
static void apply_autotune(dt_iop_module_t *self)
{
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)self->params;
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
 
  float noise = powf(2.0f, -16.0f);
 
  // Grey
  float grey = fmax(fmax(self->picked_color[0], self->picked_color[1]), self->picked_color[2]);
  p->grey_point = 100.f * grey;
 
  // Black
  float black = fmax(fmax(self->picked_color_min[0], self->picked_color_min[1]), self->picked_color_min[2]);
  float EVmin = Log2Thres(black / (p->grey_point / 100.0f), noise);
  EVmin *= (1.0f + p->security_factor / 100.0f);
 
  // White
  float white = fmax(fmax(self->picked_color_max[0], self->picked_color_max[1]), self->picked_color_max[2]);
  float EVmax = Log2Thres(white / (p->grey_point / 100.0f), noise);
  EVmax *= (1.0f + p->security_factor / 100.0f);
 
  p->shadows_range = EVmin;
  p->dynamic_range = EVmax - EVmin;
 
  dt_gui_freeze_begin();
  dt_bauhaus_slider_set(g->grey_point, p->grey_point);
  dt_bauhaus_slider_set(g->shadows_range, p->shadows_range);
  dt_bauhaus_slider_set(g->dynamic_range, p->dynamic_range);
  dt_gui_freeze_end();
 
  dt_dev_add_history_item(self->dev, self, TRUE, TRUE);
}
 
 
void gui_changed(dt_iop_module_t *self, GtkWidget *w, void *previous)
{
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)self->params;
 
  if(w == g->mode)
  {
    /* grey_point/shadows_range/dynamic_range/auto_button live on the "log" stack
       page. Switching mode can hide that page while a picker stays active,
       sampling/drawing on the image for a control the user can no longer see or
       turn off from this widget. */
    dt_iop_color_picker_reset(self, FALSE);
 
    if(p->mode == PROFILEGAMMA_LOG)
    {
      gtk_stack_set_visible_child_name(GTK_STACK(g->mode_stack), "log");
    }
    else
    {
      gtk_stack_set_visible_child_name(GTK_STACK(g->mode_stack), "gamma");
    }
  }
  else if(w == g->security_factor)
  {
    float prev = *(float *)previous;
    float ratio = (p->security_factor - prev) / (prev + 100.0f);
 
    float EVmin = p->shadows_range;
    EVmin = EVmin + ratio * EVmin;
 
    float EVmax = p->dynamic_range + p->shadows_range;
    EVmax = EVmax + ratio * EVmax;
 
    p->dynamic_range = EVmax - EVmin;
    p->shadows_range = EVmin;
 
    dt_gui_freeze_begin();
    dt_bauhaus_slider_set(g->dynamic_range, p->dynamic_range);
    dt_bauhaus_slider_set(g->shadows_range, p->shadows_range);
    dt_gui_freeze_end();
  }
}
 
void color_picker_apply(dt_iop_module_t *self, GtkWidget *picker, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
  if     (picker == g->grey_point)
    apply_auto_grey(self);
  else if(picker == g->shadows_range)
    apply_auto_black(self);
  else if(picker == g->dynamic_range)
    apply_auto_dynamic_range(self);
  else if(picker == g->auto_button)
    apply_autotune(self);
  else
    fprintf(stderr, "[profile_gamma] unknown color picker\n");
}
 
void commit_params(dt_iop_module_t *self, dt_iop_params_t *p1, dt_dev_pixelpipe_t *pipe,
                   dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_profilegamma_params_t *p = (dt_iop_profilegamma_params_t *)p1;
  dt_iop_profilegamma_data_t *d = (dt_iop_profilegamma_data_t *)piece->data;
 
  const float linear = p->linear;
  const float gamma = p->gamma;
 
  d->linear = p->linear;
  d->gamma = p->gamma;
 
  float a, b, c, g;
  if(gamma == 1.0)
  {
    __OMP_PARALLEL_FOR__()
    for(int k = 0; k < 0x10000; k++) d->table[k] = 1.0 * k / 0x10000;
  }
  else
  {
    if(linear == 0.0)
    {
      __OMP_PARALLEL_FOR__()
      for(int k = 0; k < 0x10000; k++) d->table[k] = powf(1.00 * k / 0x10000, gamma);
    }
    else
    {
      if(linear < 1.0)
      {
        g = gamma * (1.0 - linear) / (1.0 - gamma * linear);
        a = 1.0 / (1.0 + linear * (g - 1));
        b = linear * (g - 1) * a;
        c = powf(a * linear + b, g) / linear;
      }
      else
      {
        a = b = g = 0.0;
        c = 1.0;
      }
      __OMP_PARALLEL_FOR__()
      for(int k = 0; k < 0x10000; k++)
      {
        float tmp;
        if(k < 0x10000 * linear)
          tmp = c * k / 0x10000;
        else
          tmp = powf(a * k / 0x10000 + b, g);
        d->table[k] = tmp;
      }
    }
  }
 
  // now the extrapolation stuff:
  const float x[4] = { 0.7f, 0.8f, 0.9f, 1.0f };
  const float y[4]
      = { d->table[CLAMP((int)(x[0] * 0x10000ul), 0, 0xffff)],
          d->table[CLAMP((int)(x[1] * 0x10000ul), 0, 0xffff)],
          d->table[CLAMP((int)(x[2] * 0x10000ul), 0, 0xffff)],
          d->table[CLAMP((int)(x[3] * 0x10000ul), 0, 0xffff)] };
  dt_iop_estimate_exp(x, y, 4, d->unbounded_coeffs);
 
  d->dynamic_range = p->dynamic_range;
  d->grey_point = p->grey_point;
  d->shadows_range = p->shadows_range;
  d->security_factor = p->security_factor;
  d->mode = p->mode;
 
  //piece->process_cl_ready = 1;
 
  // no OpenCL for log yet.
  //if(d->mode == PROFILEGAMMA_LOG) piece->process_cl_ready = 0;
}
 
void init_pipe(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  piece->data = dt_calloc_align(sizeof(dt_iop_profilegamma_data_t));
  piece->data_size = sizeof(dt_iop_profilegamma_data_t);
}
 
void cleanup_pipe(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(dt_iop_module_t *self)
{
  dt_iop_color_picker_reset(self, TRUE);
}
 
void gui_update(dt_iop_module_t *self)
{
  dt_iop_profilegamma_gui_data_t *g = (dt_iop_profilegamma_gui_data_t *)dt_iop_gui_data(self);
 
  dt_iop_color_picker_reset(self, TRUE);
 
  gui_changed(self, g->mode, 0);
}
 
void gui_init(dt_iop_module_t *self)
{
  dt_iop_profilegamma_gui_data_t *g = IOP_GUI_ALLOC(profilegamma);
 
  // prepare the modes widgets stack
  g->mode_stack = gtk_stack_new();
  gtk_stack_set_homogeneous(GTK_STACK(g->mode_stack), FALSE);
 
  /**** GAMMA MODE ***/
 
  GtkWidget *vbox_gamma = self->gui->widget = GTK_WIDGET(gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING));
 
  g->linear = dt_bauhaus_slider_from_params(self, N_("linear"));
  dt_bauhaus_slider_set_digits(g->linear, 4);
  gtk_widget_set_tooltip_text(g->linear, _("linear part"));
 
  g->gamma = dt_bauhaus_slider_from_params(self, N_("gamma"));
  dt_bauhaus_slider_set_digits(g->gamma, 4);
  gtk_widget_set_tooltip_text(g->gamma, _("gamma exponential factor"));
 
  gtk_stack_add_named(GTK_STACK(g->mode_stack), vbox_gamma, "gamma");
 
  /**** LOG MODE ****/
 
  GtkWidget *vbox_log = self->gui->widget = GTK_WIDGET(gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING));
 
  g->grey_point
      = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, dt_bauhaus_slider_from_params(self, "grey_point"));
  dt_bauhaus_slider_set_format(g->grey_point, "%");
  gtk_widget_set_tooltip_text(g->grey_point, _("adjust to match the average luma of the subject"));
 
  g->shadows_range
      = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, dt_bauhaus_slider_from_params(self, "shadows_range"));
  dt_bauhaus_slider_set_soft_max(g->shadows_range, 0.0);
  dt_bauhaus_slider_set_format(g->shadows_range, _(" EV"));
  gtk_widget_set_tooltip_text(g->shadows_range, _("number of stops between middle gray and pure black\nthis is a reading a posemeter would give you on the scene"));
 
  g->dynamic_range
      = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, dt_bauhaus_slider_from_params(self, "dynamic_range"));
  dt_bauhaus_slider_set_soft_range(g->dynamic_range, 0.5, 16.0);
  dt_bauhaus_slider_set_format(g->dynamic_range, _(" EV"));
  gtk_widget_set_tooltip_text(g->dynamic_range, _("number of stops between pure black and pure white\nthis is a reading a posemeter would give you on the scene"));
 
  gtk_box_pack_start(GTK_BOX(vbox_log), dt_ui_section_label_new(_("optimize automatically")), FALSE, FALSE, 0);
 
  g->security_factor = dt_bauhaus_slider_from_params(self, "security_factor");
  dt_bauhaus_slider_set_format(g->security_factor, "%");
  gtk_widget_set_tooltip_text(g->security_factor, _("enlarge or shrink the computed dynamic range\nthis is useful when noise perturbates the measurements"));
 
  g->auto_button = dt_color_picker_new(self, DT_COLOR_PICKER_AREA, dt_bauhaus_combobox_new(dt_bauhaus_get_global(), DT_GUI_MODULE(self)));
  dt_bauhaus_widget_set_label(g->auto_button, N_("auto tune levels"));
  gtk_widget_set_tooltip_text(g->auto_button, _("make an optimization with some guessing"));
  gtk_box_pack_start(GTK_BOX(vbox_log), g->auto_button, TRUE, TRUE, 0);
 
  gtk_stack_add_named(GTK_STACK(g->mode_stack), vbox_log, "log");
 
  // start building top level widget
  self->gui->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  g->mode = dt_bauhaus_combobox_from_params(self, N_("mode"));
  gtk_widget_set_tooltip_text(g->mode, _("tone mapping method"));
 
  gtk_box_pack_start(GTK_BOX(self->gui->widget), g->mode_stack, TRUE, TRUE, 0);
}
 
 
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