gimp/plug-ins/common/autostretch_hsv.c

/* Autostretch HSV 0.10 --- image filter plug-in for The Gimp image
 * manipulation program
 *
 * Copyright (C) 1997 Scott Goehring
 * Copyright (C) 1996 Federico Mena Quintero
 *
 * You can contact me at scott@poverty.bloomington.in.us
 * You can contact the original The Gimp authors at gimp@xcf.berkeley.edu
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/* This simple plug-in does an automatic contrast stretch.  For each
   channel in the image, it finds the minimum and maximum values... it
   uses those values to stretch the individual histograms to the full
   contrast range.  For some images it may do just what you want; for
   others it may be total crap :) This version operates in HSV space
   and preserves hue, unlike the original Contrast Autostretch. */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>

#include <libgimp/gimp.h>

#include "libgimp/stdplugins-intl.h"


/* Declare local functions.
 */
static void   query                   (void);
static void   run                     (const gchar      *name,
                                       gint              nparams,
                                       const GimpParam  *param,
                                       gint             *nreturn_vals,
                                       GimpParam       **return_vals);

static void   autostretch_hsv         (GimpDrawable  *drawable);
static void   indexed_autostretch_hsv (gint32         image_ID);

static GimpRunMode    run_mode;

GimpPlugInInfo PLUG_IN_INFO =
{
  NULL,  /* init_proc  */
  NULL,  /* quit_proc  */
  query, /* query_proc */
  run,   /* run_proc   */
};


MAIN ()

static void
query (void)
{
  static GimpParamDef args[] =
  {
    { GIMP_PDB_INT32, "run_mode", "Interactive, non-interactive" },
    { GIMP_PDB_IMAGE, "image", "Input image" },
    { GIMP_PDB_DRAWABLE, "drawable", "Input drawable" }
  };

  gimp_install_procedure ("plug_in_autostretch_hsv",
			  "Automatically stretch the contrast of the specified "
			  "drawable to cover all possible ranges.",
			  "This simple plug-in does an automatic contrast "
			  "stretch.  For each channel in the image, it finds "
			  "the minimum and maximum values... it uses those "
			  "values to stretch the individual histograms to the "
			  "full contrast range.  For some images it may do "
			  "just what you want; for others it may be total "
			  "crap :).  This version differs from Contrast "
			  "Autostretch in that it works in HSV space, and "
			  "preserves hue.",
			  "Scott Goehring and Federico Mena Quintero",
			  "Scott Goehring and Federico Mena Quintero",
			  "1997",
			  N_("<Image>/Layer/Colors/Auto/Stretch _HSV"),
			  "RGB*, INDEXED*",
			  GIMP_PLUGIN,
			  G_N_ELEMENTS (args), 0,
			  args, NULL);
}

static void
run (const gchar      *name,
     gint              nparams,
     const GimpParam  *param,
     gint             *nreturn_vals,
     GimpParam       **return_vals)
{
  static GimpParam   values[1];
  GimpDrawable      *drawable;
  GimpPDBStatusType  status = GIMP_PDB_SUCCESS;

  gint32 image_ID;

  INIT_I18N();

  run_mode = param[0].data.d_int32;

  /*  Get the specified drawable  */
  drawable = gimp_drawable_get (param[2].data.d_drawable);
  image_ID = param[1].data.d_image;

  /*  Make sure that the drawable is gray or RGB color  */
  if (gimp_drawable_is_rgb (drawable->drawable_id) ||
      gimp_drawable_is_gray (drawable->drawable_id))
    {
      gimp_progress_init (_("Auto-Stretching HSV..."));
      gimp_tile_cache_ntiles (2 * (drawable->width / gimp_tile_width () + 1));
      autostretch_hsv (drawable);

      if (run_mode != GIMP_RUN_NONINTERACTIVE)
	gimp_displays_flush ();
    }
  else if (gimp_drawable_is_indexed (drawable->drawable_id))
    {
      indexed_autostretch_hsv (image_ID);

      if (run_mode != GIMP_RUN_NONINTERACTIVE)
	gimp_displays_flush ();
    }
  else
    {
      /* gimp_message ("autostretch_hsv: cannot operate on indexed color images"); */
      status = GIMP_PDB_EXECUTION_ERROR;
    }

  *nreturn_vals = 1;
  *return_vals = values;

  values[0].type = GIMP_PDB_STATUS;
  values[0].data.d_status = status;

  gimp_drawable_detach (drawable);
}

typedef struct {
  double shi;
  double slo;
  double vhi;
  double vlo;
} AutostretchData;

static void 
find_max (guchar *src, gint bpp, AutostretchData *data)
{
  double h, s, v;

  gimp_rgb_to_hsv4(src, &h, &s, &v);
  if (s > data->shi) data->shi = s;
  if (s < data->slo) data->slo = s;
  if (v > data->vhi) data->vhi = v;
  if (v < data->vlo) data->vlo = v;
}

static void 
autostretch_hsv_func (guchar *src, guchar *dest, gint bpp, 
		      AutostretchData *data)
{
  double h, s, v;

  gimp_rgb_to_hsv4(src, &h, &s, &v);
  if (data->shi != data->slo)
    s = (s - data->slo) / (data->shi - data->slo);
  if (data->vhi != data->vlo)
    v = (v - data->vlo) / (data->vhi - data->vlo);
  gimp_hsv_to_rgb4(dest, h, s, v);
  
  if (bpp == 4)
    dest[3] = src[3];
}

static void
indexed_autostretch_hsv (gint32 image_ID)  /* a.d.m. */
{
  guchar *cmap;
  AutostretchData data = {0.0, 1.0, 0.0, 1.0};
  gint ncols,i;

  cmap = gimp_image_get_cmap (image_ID, &ncols);

  if (cmap==NULL)
    {
      fprintf(stderr, "autostretch_hsv: cmap was NULL!  Quitting...\n");
      gimp_quit();
    }

  for (i = 0; i < ncols; i++)
    {
      find_max (&cmap[i * 3], 3, &data);
    }

  for (i = 0; i < ncols; i++)
    {
      autostretch_hsv_func (&cmap[i * 3], &cmap[i * 3], 3, &data);
    }

  gimp_image_set_cmap (image_ID, cmap, ncols);
}

static void
autostretch_hsv (GimpDrawable *drawable)
{
  AutostretchData data = {0.0, 1.0, 0.0, 1.0};

  gimp_rgn_iterate1 (drawable, run_mode, (GimpRgnFunc1) find_max, &data);
  gimp_rgn_iterate2 (drawable, run_mode, (GimpRgnFunc2) autostretch_hsv_func, 
		     &data);
}