/*
    This file is part of darktable,
    Copyright (C) 2010-2026 darktable developers.

    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/>.
*/

//
// A tonemapping module using Durand's process :
// <http://graphics.lcs.mit.edu/~fredo/PUBLI/Siggraph2002/>
//
// Use andrew adams et al.'s permutohedral lattice, for fast bilateral filtering
// See Permutohedral.h
//

#define __STDC_FORMAT_MACROS

#include <math.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <gtk/gtk.h>

#include "bauhaus/bauhaus.h"
#include "control/control.h"
#include "develop/develop.h"
#include "develop/imageop.h"
#include "develop/imageop_gui.h"
#include "gui/accelerators.h"
#include "gui/gtk.h"
#include "iop/iop_api.h"

#include "iop/Permutohedral.h"

G_BEGIN_DECLS

DT_MODULE_INTROSPECTION(1, dt_iop_tonemapping_params_t)

typedef struct dt_iop_tonemapping_params_t
{
  float contrast; // $MIN: 1.0 $MAX: 5.0 $DEFAULT: 2.5 $DESCRIPTION: "contrast compression"
  float Fsize;    // $MIN: 0.0 $MAX: 100.0 $DEFAULT: 30 $DESCRIPTION: "spatial extent"
} dt_iop_tonemapping_params_t;

typedef struct dt_iop_tonemapping_gui_data_t
{
  GtkWidget *contrast, *Fsize;
} dt_iop_tonemapping_gui_data_t;

typedef struct dt_iop_tonemapping_data_t
{
  float contrast, Fsize;
} dt_iop_tonemapping_data_t;

const char *name()
{
  return _("tone mapping");
}


int default_group()
{
  return IOP_GROUP_TONE | IOP_GROUP_GRADING;
}

int flags()
{
  return IOP_FLAGS_SUPPORTS_BLENDING | IOP_FLAGS_DEPRECATED;
}

const char *deprecated_msg()
{
  return _("this module is deprecated. please use the local contrast or tone equalizer module instead.");
}

dt_iop_colorspace_type_t default_colorspace(dt_iop_module_t *self,
                                            dt_dev_pixelpipe_t *pipe,
                                            dt_dev_pixelpipe_iop_t *piece)
{
  return IOP_CS_RGB;
}

void process(dt_iop_module_t *self, dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
             void *const ovoid, const dt_iop_roi_t *const roi_in, const dt_iop_roi_t *const roi_out)
{
  dt_iop_tonemapping_data_t *data = (dt_iop_tonemapping_data_t *)piece->data;
  const int ch = piece->colors;

  int width, height;
  float inv_sigma_s;
  const float inv_sigma_r = 1.0 / 0.4;

  width = roi_in->width;
  height = roi_in->height;
  const size_t size = (size_t)width * height;
  const float iw = piece->buf_in.width * roi_out->scale;
  const float ih = piece->buf_in.height * roi_out->scale;

  inv_sigma_s = (data->Fsize / 100.0) * fminf(iw, ih);
  if(inv_sigma_s < 3.0) inv_sigma_s = 3.0;
  inv_sigma_s = 1.0 / inv_sigma_s;

  PermutohedralLattice<3, 2> lattice(size, dt_get_num_threads());

// Build I=log(L)
// and splat into the lattice
  DT_OMP_FOR(shared(lattice))
  for(int j = 0; j < height; j++)
  {
    size_t index = (size_t)j * width;
    const int thread = omp_get_thread_num();
    const float *in = (const float *)ivoid + (size_t)j * width * ch;
    for(int i = 0; i < width; i++, index++, in += ch)
    {
      float L = 0.2126 * in[0] + 0.7152 * in[1] + 0.0722 * in[2];
      if(L <= 0.0) L = 1e-6;
      L = logf(L);
      float pos[3] = { i * inv_sigma_s, j * inv_sigma_s, L * inv_sigma_r };
      float val[2] = { L, 1.0 };
      lattice.splat(pos, val, index, thread);
    }
  }

  lattice.merge_splat_threads();

  // blur the lattice
  lattice.blur();

  //
  // Durand process :
  // r=R/(input intensity), g=G/input intensity, B=B/input intensity
  // log(base)=Bilateral(log(input intensity))
  // log(detail)=log(input intensity)-log(base)
  // log (output intensity)=log(base)*compressionfactor+log(detail)
  // R output = r*exp(log(output intensity)), etc.
  //
  // Simplyfing :
  // R output = R/(input intensity)*exp(log(output intensity))
  //          = R*exp(log(output intensity)-log(input intensity))
  //          = R*exp(log(base)*compressionfactor+log(input intensity)-log(base)-log(input intensity))
  //          = R*exp(log(base)*(compressionfactor-1))
  //
  // Plus :
  //  Before compressing the base intensity , we remove average base intensity in order to not have
  //  variable average intensity when varying compression factor.
  //  after compression we subtract 2.0 to have an average intensity at middle tone.
  //

  const float contr = 1. / data->contrast;
  DT_OMP_FOR(shared(lattice))
  for(int j = 0; j < height; j++)
  {
    size_t index = (size_t)j * width;
    const float *in = (const float *)ivoid + (size_t)j * width * ch;
    float *out = (float *)ovoid + (size_t)j * width * ch;
    for(int i = 0; i < width; i++, index++, in += ch, out += ch)
    {
      float val[2];
      lattice.slice(val, index);
      float L = 0.2126 * in[0] + 0.7152 * in[1] + 0.0722 * in[2];
      if(L <= 0.0) L = 1e-6;
      L = logf(L);
      const float B = val[0] / val[1];
      const float detail = L - B;
      const float Ln = expf(B * (contr - 1.0f) + detail - 1.0f);

      out[0] = in[0] * Ln;
      out[1] = in[1] * Ln;
      out[2] = in[2] * Ln;
      out[3] = in[3];
    }
  }
  // also process the clipping point, as good as we can without knowing
  // the local environment (i.e. assuming detail == 0)
  float *pmax = piece->pipe->dsc.processed_maximum;
  float L = 0.2126 * pmax[0] + 0.7152 * pmax[1] + 0.0722 * pmax[2];
  if(L <= 0.0) L = 1e-6;
  L = logf(L);
  const float Ln = expf(L * (contr - 1.0f) - 1.0f);
  for(int k = 0; k < 3; k++) pmax[k] *= Ln;
}


// GUI
//
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_tonemapping_params_t *p = (dt_iop_tonemapping_params_t *)p1;
  dt_iop_tonemapping_data_t *d = (dt_iop_tonemapping_data_t *)piece->data;
  d->contrast = p->contrast;
  d->Fsize = p->Fsize;
}

void init_pipe(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  piece->data = malloc(sizeof(dt_iop_tonemapping_data_t));
}

void cleanup_pipe(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  free(piece->data);
  piece->data = NULL;
}

void gui_init(dt_iop_module_t *self)
{
  dt_iop_tonemapping_gui_data_t *g = IOP_GUI_ALLOC(tonemapping);

  g->contrast = dt_bauhaus_slider_from_params(self, "contrast");

  g->Fsize = dt_bauhaus_slider_from_params(self, "Fsize");
  dt_bauhaus_slider_set_format(g->Fsize, "%");
}

G_END_DECLS

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// modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
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