lowpass.c

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/*
  This file is part of darktable,
  Copyright (C) 2011 Brian Teague.
  Copyright (C) 2011 Henrik Andersson.
  Copyright (C) 2011-2013, 2016 johannes hanika.
  Copyright (C) 2011 Jérémy Rosen.
  Copyright (C) 2011 Robert Bieber.
  Copyright (C) 2011-2014, 2016, 2019 Tobias Ellinghaus.
  Copyright (C) 2011-2017 Ulrich Pegelow.
  Copyright (C) 2012 Edouard Gomez.
  Copyright (C) 2012 Richard Wonka.
  Copyright (C) 2013 Pascal de Bruijn.
  Copyright (C) 2013, 2018, 2020, 2022 Pascal Obry.
  Copyright (C) 2013-2016 Roman Lebedev.
  Copyright (C) 2015 Pedro Côrte-Real.
  Copyright (C) 2017, 2020 Heiko Bauke.
  Copyright (C) 2018-2020, 2022-2023, 2025-2026 Aurélien PIERRE.
  Copyright (C) 2018 Edgardo Hoszowski.
  Copyright (C) 2018 Maurizio Paglia.
  Copyright (C) 2018 rawfiner.
  Copyright (C) 2019 Andreas Schneider.
  Copyright (C) 2020 Aldric Renaudin.
  Copyright (C) 2020, 2022 Diederik Ter Rahe.
  Copyright (C) 2020-2021 Hubert Kowalski.
  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 "common/darktable.h"
#include "config.h"
#endif
#include "bauhaus/bauhaus.h"
#include "common/bilateral.h"
#include "common/bilateralcl.h"
#include "common/debug.h"
#include "common/gaussian.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/imageop_gui.h"
#include "develop/tiling.h"
 
#include "gui/gtk.h"
#include "gui/presets.h"
#include "iop/iop_api.h"
#include <assert.h>
#include <gtk/gtk.h>
#include <stdlib.h>
#include <string.h>
 
#include <inttypes.h>
 
DT_MODULE_INTROSPECTION(4, dt_iop_lowpass_params_t)
 
typedef enum dt_iop_lowpass_algo_t
{
  LOWPASS_ALGO_GAUSSIAN, // $DESCRIPTION: "gaussian"
  LOWPASS_ALGO_BILATERAL // $DESCRIPTION: "bilateral filter"
} dt_iop_lowpass_algo_t;
 
/* legacy version 1 params */
typedef struct dt_iop_lowpass_params1_t
{
  dt_gaussian_order_t order;
  float radius;
  float contrast;
  float saturation;
} dt_iop_lowpass_params1_t;
 
typedef struct dt_iop_lowpass_params2_t
{
  dt_gaussian_order_t order;
  float radius;
  float contrast;
  float brightness;
  float saturation;
} dt_iop_lowpass_params2_t;
 
typedef struct dt_iop_lowpass_params3_t
{
  dt_gaussian_order_t order;
  float radius;
  float contrast;
  float brightness;
  float saturation;
  int unbound;
} dt_iop_lowpass_params3_t;
 
typedef struct dt_iop_lowpass_params_t
{
  dt_gaussian_order_t order; // $DEFAULT: 0
  float radius;     // $MIN: 0.1 $MAX: 500.0 $DEFAULT: 10.0
  float contrast;   // $MIN: -3.0 $MAX: 3.0 $DEFAULT: 1.0
  float brightness; // $MIN: -3.0 $MAX: 3.0 $DEFAULT: 0.0
  float saturation; // $MIN: -3.0 $MAX: 3.0 $DEFAULT: 1.0
  dt_iop_lowpass_algo_t lowpass_algo; // $DEFAULT: LOWPASS_ALGO_GAUSSIAN $DESCRIPTION: "soften with"
  int unbound; // $DEFAULT: 1
} dt_iop_lowpass_params_t;
 
 
typedef struct dt_iop_lowpass_gui_data_t
{
  GtkWidget *radius;
  GtkWidget *contrast;
  GtkWidget *brightness;
  GtkWidget *saturation;
  GtkWidget *order;
  GtkWidget *lowpass_algo;
} dt_iop_lowpass_gui_data_t;
 
typedef struct dt_iop_lowpass_data_t
{
  dt_gaussian_order_t order;
  float radius;
  float contrast;
  float brightness;
  float saturation;
  dt_iop_lowpass_algo_t lowpass_algo;
  int unbound;
  float ctable[0x10000];      // precomputed look-up table for contrast curve
  float cunbounded_coeffs[3]; // approximation for extrapolation of contrast curve
  float ltable[0x10000];      // precomputed look-up table for brightness curve
  float lunbounded_coeffs[3]; // approximation for extrapolation of brightness curve
} dt_iop_lowpass_data_t;
 
typedef struct dt_iop_lowpass_global_data_t
{
  int kernel_lowpass_mix;
} dt_iop_lowpass_global_data_t;
 
 
const char *name()
{
  return _("lowpass");
}
 
const char **description(struct dt_iop_module_t *self)
{
  return dt_iop_set_description(self, _("isolate low frequencies in the image"),
                                      _("creative"),
                                      _("linear or non-linear, Lab, scene-referred"),
                                      _("frequential, Lab"),
                                      _("special, Lab, scene-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_EFFECTS;
}
 
int default_colorspace(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece)
{
  return IOP_CS_LAB;
}
 
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 == 4)
  {
    const dt_iop_lowpass_params1_t *old = old_params;
    dt_iop_lowpass_params_t *new = new_params;
    new->order = old->order;
    new->radius = fabs(old->radius);
    new->contrast = old->contrast;
    new->saturation = old->saturation;
    new->brightness = 0.0f;
    new->lowpass_algo = old->radius < 0.0f ? LOWPASS_ALGO_BILATERAL : LOWPASS_ALGO_GAUSSIAN;
    new->unbound = 0;
 
    return 0;
  }
  if(old_version == 2 && new_version == 4)
  {
    const dt_iop_lowpass_params2_t *old = old_params;
    dt_iop_lowpass_params_t *new = new_params;
    new->order = old->order;
    new->radius = fabs(old->radius);
    new->contrast = old->contrast;
    new->saturation = old->saturation;
    new->brightness = old->brightness;
    new->lowpass_algo = old->radius < 0.0f ? LOWPASS_ALGO_BILATERAL : LOWPASS_ALGO_GAUSSIAN;
    new->unbound = 0;
 
    return 0;
  }
  if(old_version == 3 && new_version == 4)
  {
    const dt_iop_lowpass_params3_t *old = old_params;
    dt_iop_lowpass_params_t *new = new_params;
    new->order = old->order;
    new->radius = fabs(old->radius);
    new->contrast = old->contrast;
    new->saturation = old->saturation;
    new->brightness = old->brightness;
    new->lowpass_algo = old->radius < 0.0f ? LOWPASS_ALGO_BILATERAL : LOWPASS_ALGO_GAUSSIAN;
    new->unbound = old->unbound;
 
    return 0;
  }
  return 1;
}
 
 
#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_in = &piece->roi_in;
  (void)piece->roi_out;
  dt_iop_lowpass_data_t *d = (dt_iop_lowpass_data_t *)piece->data;
  dt_iop_lowpass_global_data_t *gd = (dt_iop_lowpass_global_data_t *)self->global_data;
 
  cl_int err = -999;
  const int devid = pipe->devid;
 
  const int width = roi_in->width;
  const int height = roi_in->height;
  const int channels = piece->dsc_in.channels;
 
  const float radius = fmax(0.1f, d->radius);
  const float sigma = radius * roi_in->scale;
  const float saturation = d->saturation;
  const int order = d->order;
  const int unbound = d->unbound;
 
  cl_mem dev_cm = NULL;
  cl_mem dev_ccoeffs = NULL;
  cl_mem dev_lm = NULL;
  cl_mem dev_lcoeffs = NULL;
  cl_mem dev_tmp = NULL;
 
  dt_gaussian_cl_t *g = NULL;
  dt_bilateral_cl_t *b = NULL;
 
  float Labmax[] = { 100.0f, 128.0f, 128.0f, 1.0f };
  float Labmin[] = { 0.0f, -128.0f, -128.0f, 0.0f };
 
  if(unbound)
  {
    for(int k = 0; k < 4; k++) Labmax[k] = INFINITY;
    for(int k = 0; k < 4; k++) Labmin[k] = -INFINITY;
  }
 
  if(d->lowpass_algo == LOWPASS_ALGO_GAUSSIAN)
  {
    g = dt_gaussian_init_cl(devid, width, height, channels, Labmax, Labmin, sigma, order);
    if(IS_NULL_PTR(g)) goto error;
    err = dt_gaussian_blur_cl(g, dev_in, dev_out);
    if(err != CL_SUCCESS) goto error;
    dt_gaussian_free_cl(g);
    g = NULL;
  }
  else
  {
    const float sigma_r = 100.0f; // does not depend on scale
    const float sigma_s = sigma;
    const float detail = -1.0f; // we want the bilateral base layer
 
    b = dt_bilateral_init_cl(devid, width, height, sigma_s, sigma_r);
    if(IS_NULL_PTR(b)) goto error;
    err = dt_bilateral_splat_cl(b, dev_in);
    if(err != CL_SUCCESS) goto error;
    err = dt_bilateral_blur_cl(b);
    if(err != CL_SUCCESS) goto error;
    err = dt_bilateral_slice_cl(b, dev_in, dev_out, detail);
    if(err != CL_SUCCESS) goto error;
    dt_bilateral_free_cl(b);
    b = NULL; // make sure we don't clean it up twice
  }
 
  dev_tmp = dt_opencl_alloc_device(devid, width, height, sizeof(float) * 4);
  if(IS_NULL_PTR(dev_tmp)) goto error;
 
  dev_cm = dt_opencl_copy_host_to_device(devid, d->ctable, 256, 256, sizeof(float));
  if(IS_NULL_PTR(dev_cm)) goto error;
 
  dev_ccoeffs = dt_opencl_copy_host_to_device_constant(devid, sizeof(float) * 3, d->cunbounded_coeffs);
  if(IS_NULL_PTR(dev_ccoeffs)) goto error;
 
  dev_lm = dt_opencl_copy_host_to_device(devid, d->ltable, 256, 256, sizeof(float));
  if(IS_NULL_PTR(dev_lm)) goto error;
 
  dev_lcoeffs = dt_opencl_copy_host_to_device_constant(devid, sizeof(float) * 3, d->lunbounded_coeffs);
  if(IS_NULL_PTR(dev_lcoeffs)) goto error;
 
  size_t origin[] = { 0, 0, 0 };
  size_t region[] = { width, height, 1 };
  err = dt_opencl_enqueue_copy_image(devid, dev_out, dev_tmp, origin, origin, region);
  if(err != CL_SUCCESS) goto error;
 
  const size_t sizes[] = { ROUNDUPDWD(width, devid), ROUNDUPDHT(height, devid), 1 };
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 0, sizeof(cl_mem), (void *)&dev_tmp);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 1, sizeof(cl_mem), (void *)&dev_out);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 2, sizeof(int), (void *)&width);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 3, sizeof(int), (void *)&height);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 4, sizeof(float), (void *)&saturation);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 5, sizeof(cl_mem), (void *)&dev_cm);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 6, sizeof(cl_mem), (void *)&dev_ccoeffs);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 7, sizeof(cl_mem), (void *)&dev_lm);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 8, sizeof(cl_mem), (void *)&dev_lcoeffs);
  dt_opencl_set_kernel_arg(devid, gd->kernel_lowpass_mix, 9, sizeof(int), (void *)&unbound);
 
  err = dt_opencl_enqueue_kernel_2d(devid, gd->kernel_lowpass_mix, sizes);
  if(err != CL_SUCCESS) goto error;
 
  dt_opencl_release_mem_object(dev_tmp);
  dt_opencl_release_mem_object(dev_lcoeffs);
  dt_opencl_release_mem_object(dev_lm);
  dt_opencl_release_mem_object(dev_ccoeffs);
  dt_opencl_release_mem_object(dev_cm);
 
  return TRUE;
 
error:
  if(g) dt_gaussian_free_cl(g);
  if(b) dt_bilateral_free_cl(b);
 
  dt_opencl_release_mem_object(dev_tmp);
  dt_opencl_release_mem_object(dev_lcoeffs);
  dt_opencl_release_mem_object(dev_lm);
  dt_opencl_release_mem_object(dev_ccoeffs);
  dt_opencl_release_mem_object(dev_cm);
  dt_print(DT_DEBUG_OPENCL, "[opencl_lowpass] couldn't enqueue kernel! %d\n", err);
  return FALSE;
}
#endif
 
void tiling_callback(struct dt_iop_module_t *self, const struct dt_dev_pixelpipe_t *pipe, const struct dt_dev_pixelpipe_iop_t *piece, struct dt_develop_tiling_t *tiling)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  dt_iop_lowpass_data_t *d = (dt_iop_lowpass_data_t *)piece->data;
  (void)pipe;
 
  const float radius = fmax(0.1f, d->radius);
  const float sigma = radius * roi_in->scale;
  const float sigma_r = 100.0f; // does not depend on scale
  const float sigma_s = sigma;
 
  const int width = roi_in->width;
  const int height = roi_in->height;
  const int channels = piece->dsc_in.channels;
 
  const size_t basebuffer = sizeof(float) * channels * width * height;
 
  if(d->lowpass_algo == LOWPASS_ALGO_BILATERAL)
  {
    // bilateral filter
    tiling->factor = 2.0f + fmax(1.0f, (float)dt_bilateral_memory_use(width, height, sigma_s, sigma_r) / basebuffer);
    tiling->maxbuf
        = fmax(1.0f, (float)dt_bilateral_singlebuffer_size(width, height, sigma_s, sigma_r) / basebuffer);
  }
  else
  {
    // gaussian blur
    tiling->factor = 2.0f + fmax(1.0f, (float)dt_gaussian_memory_use(width, height, channels) / basebuffer);
#ifdef HAVE_OPENCL
    tiling->factor_cl = 2.0f + fmax(1.0f, (float)dt_gaussian_memory_use_cl(width, height, channels) / basebuffer);
#endif
    tiling->maxbuf = fmax(1.0f, (float)dt_gaussian_singlebuffer_size(width, height, channels) / basebuffer);
  }
  tiling->overhead = 0;
  tiling->overlap = ceilf(4 * sigma);
  tiling->xalign = 1;
  tiling->yalign = 1;
  return;
}
 
__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;
  dt_iop_lowpass_data_t *data = (dt_iop_lowpass_data_t *)piece->data;
  float *in = (float *)ivoid;
  float *out = (float *)ovoid;
 
 
  const int width = roi_in->width;
  const int height = roi_in->height;
  const int ch = piece->dsc_in.channels;
 
  const float radius = fmax(0.1f, data->radius);
  const float sigma = radius * roi_in->scale;
  const int order = data->order;
  const int unbound = data->unbound;
 
  float Labmax[] = { 100.0f, 128.0f, 128.0f, 1.0f };
  float Labmin[] = { 0.0f, -128.0f, -128.0f, 0.0f };
 
  if(unbound)
  {
    for(int k = 0; k < 4; k++) Labmax[k] = INFINITY;
    for(int k = 0; k < 4; k++) Labmin[k] = -INFINITY;
  }
 
  if(data->lowpass_algo == LOWPASS_ALGO_GAUSSIAN)
  {
    dt_gaussian_t *g = dt_gaussian_init(width, height, ch, Labmax, Labmin, sigma, order);
    if(IS_NULL_PTR(g)) return 1;
    dt_gaussian_blur_4c(g, in, out);
    dt_gaussian_free(g);
  }
  else
  {
    const float sigma_r = 100.0f; // d->sigma_r; // does not depend on scale
    const float sigma_s = sigma;
    const float detail = -1.0f; // we want the bilateral base layer
 
    dt_bilateral_t *b = dt_bilateral_init(width, height, sigma_s, sigma_r);
    if(IS_NULL_PTR(b)) return 1;
    dt_bilateral_splat(b, in);
    dt_bilateral_blur(b);
    dt_bilateral_slice(b, in, out, detail);
    dt_bilateral_free(b);
  }
 
  // some aliased pointers for compilers that don't yet understand operators on __m128
  const float *const Labminf = (float *)&Labmin;
  const float *const Labmaxf = (float *)&Labmax;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < (size_t)roi_out->width * roi_out->height; k++)
  {
    out[k * ch + 0] = (out[k * ch + 0] < 100.0f)
                          ? data->ctable[CLAMP((int)(out[k * ch + 0] / 100.0f * 0x10000ul), 0, 0xffff)]
                          : dt_iop_eval_exp(data->cunbounded_coeffs, out[k * ch + 0] / 100.0f);
    out[k * ch + 0] = (out[k * ch + 0] < 100.0f)
                          ? data->ltable[CLAMP((int)(out[k * ch + 0] / 100.0f * 0x10000ul), 0, 0xffff)]
                          : dt_iop_eval_exp(data->lunbounded_coeffs, out[k * ch + 0] / 100.0f);
    out[k * ch + 1] = CLAMPF(out[k * ch + 1] * data->saturation, Labminf[1],
                             Labmaxf[1]); // will not clip in unbound case (see definition of Labmax/Labmin)
    out[k * ch + 2]
        = CLAMPF(out[k * ch + 2] * data->saturation, Labminf[2], Labmaxf[2]); //                         - " -
    out[k * ch + 3] = in[k * ch + 3];
  }
  return 0;
}
 
#if 0 // gaussian order not user selectable
static void
order_changed (GtkComboBox *combo, gpointer user_data)
{
  dt_iop_module_t *self = (dt_iop_module_t *)user_data;
  if(darktable.gui->reset) return;
  dt_iop_lowpass_params_t *p = (dt_iop_lowpass_params_t *)self->params;
  p->order = gtk_combo_box_get_active(combo);
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
#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_lowpass_params_t *p = (dt_iop_lowpass_params_t *)p1;
  dt_iop_lowpass_data_t *d = (dt_iop_lowpass_data_t *)piece->data;
  d->order = p->order;
  d->radius = p->radius;
  d->contrast = p->contrast;
  d->brightness = p->brightness;
  d->saturation = p->saturation;
  d->lowpass_algo = p->lowpass_algo;
  d->unbound = p->unbound;
 
#ifdef HAVE_OPENCL
  if(d->lowpass_algo == LOWPASS_ALGO_BILATERAL)
    piece->process_cl_ready = (piece->process_cl_ready && !dt_opencl_avoid_atomics(pipe->devid));
#endif
 
 
  // generate precomputed contrast curve
  if(fabs(d->contrast) <= 1.0f)
  {
    // linear curve for contrast up to +/- 1
    for(int k = 0; k < 0x10000; k++) d->ctable[k] = d->contrast * (100.0f * k / 0x10000 - 50.0f) + 50.0f;
  }
  else
  {
    // sigmoidal curve for contrast above +/-1 1
    // going from (0,0) to (1,100) or (0,100) to (1,0), respectively
    const float boost = 5.0f;
    const float contrastm1sq = boost * (fabs(d->contrast) - 1.0f) * (fabs(d->contrast) - 1.0f);
    const float contrastscale = copysign(sqrtf(1.0f + contrastm1sq), d->contrast);
    __OMP_PARALLEL_FOR__()
    for(int k = 0; k < 0x10000; k++)
    {
      float kx2m1 = 2.0f * (float)k / 0x10000 - 1.0f;
      d->ctable[k] = 50.0f * (contrastscale * kx2m1 / sqrtf(1.0f + contrastm1sq * kx2m1 * kx2m1) + 1.0f);
    }
  }
 
  // now the extrapolation stuff for the contrast curve:
  const float xc[4] = { 0.7f, 0.8f, 0.9f, 1.0f };
  const float yc[4] = { d->ctable[CLAMP((int)(xc[0] * 0x10000ul), 0, 0xffff)],
                        d->ctable[CLAMP((int)(xc[1] * 0x10000ul), 0, 0xffff)],
                        d->ctable[CLAMP((int)(xc[2] * 0x10000ul), 0, 0xffff)],
                        d->ctable[CLAMP((int)(xc[3] * 0x10000ul), 0, 0xffff)] };
  dt_iop_estimate_exp(xc, yc, 4, d->cunbounded_coeffs);
 
 
  // generate precomputed brightness curve
  const float gamma = (d->brightness >= 0.0f) ? 1.0f / (1.0f + d->brightness) : (1.0f - d->brightness);
  __OMP_PARALLEL_FOR__()
  for(int k = 0; k < 0x10000; k++)
  {
    d->ltable[k] = 100.0f * powf((float)k / 0x10000, gamma);
  }
 
  // now the extrapolation stuff for the brightness curve:
  const float xl[4] = { 0.7f, 0.8f, 0.9f, 1.0f };
  const float yl[4] = { d->ltable[CLAMP((int)(xl[0] * 0x10000ul), 0, 0xffff)],
                        d->ltable[CLAMP((int)(xl[1] * 0x10000ul), 0, 0xffff)],
                        d->ltable[CLAMP((int)(xl[2] * 0x10000ul), 0, 0xffff)],
                        d->ltable[CLAMP((int)(xl[3] * 0x10000ul), 0, 0xffff)] };
  dt_iop_estimate_exp(xl, yl, 4, d->lunbounded_coeffs);
}
 
void init_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_lowpass_data_t *d = (dt_iop_lowpass_data_t *)dt_calloc_align(sizeof(dt_iop_lowpass_data_t));
  piece->data = (void *)d;
  piece->data_size = sizeof(dt_iop_lowpass_data_t);
  for(int k = 0; k < 0x10000; k++) d->ctable[k] = d->ltable[k] = 100.0f * k / 0x10000; // identity
}
 
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 init_global(dt_iop_module_so_t *module)
{
  const int program = 6; // gaussian.cl, from programs.conf
  dt_iop_lowpass_global_data_t *gd
      = (dt_iop_lowpass_global_data_t *)malloc(sizeof(dt_iop_lowpass_global_data_t));
  module->data = gd;
  gd->kernel_lowpass_mix = dt_opencl_create_kernel(program, "lowpass_mix");
}
 
void init_presets(dt_iop_module_so_t *self)
{
  dt_database_start_transaction(darktable.db);
 
  dt_gui_presets_add_generic(_("local contrast mask"), self->op, self->version(),
                             &(dt_iop_lowpass_params_t){ 0, 50.0f, -1.0f, 0.0f, 0.0f, LOWPASS_ALGO_GAUSSIAN, 1 },
                             sizeof(dt_iop_lowpass_params_t), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_database_release_transaction(darktable.db);
}
 
void cleanup_global(dt_iop_module_so_t *module)
{
  dt_iop_lowpass_global_data_t *gd = (dt_iop_lowpass_global_data_t *)module->data;
  dt_opencl_free_kernel(gd->kernel_lowpass_mix);
  dt_free(module->data);
}
 
void gui_init(struct dt_iop_module_t *self)
{
  dt_iop_lowpass_gui_data_t *g = IOP_GUI_ALLOC(lowpass);
 
  g->radius = dt_bauhaus_slider_from_params(self, N_("radius"));
  g->lowpass_algo = dt_bauhaus_combobox_from_params(self, "lowpass_algo");
  g->contrast = dt_bauhaus_slider_from_params(self, N_("contrast"));
  g->brightness = dt_bauhaus_slider_from_params(self, N_("brightness"));
  g->saturation = dt_bauhaus_slider_from_params(self, N_("saturation"));
 
  gtk_widget_set_tooltip_text(g->radius, _("radius of gaussian/bilateral blur"));
  gtk_widget_set_tooltip_text(g->contrast, _("contrast of lowpass filter"));
  gtk_widget_set_tooltip_text(g->brightness, _("brightness adjustment of lowpass filter"));
  gtk_widget_set_tooltip_text(g->saturation, _("color saturation of lowpass filter"));
  gtk_widget_set_tooltip_text(g->lowpass_algo, _("which filter to use for blurring"));
 
#if 0 // gaussian order not user selectable
  g_signal_connect (G_OBJECT (g->order), "changed",
                    G_CALLBACK (order_changed), self);
#endif
}
 
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