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/* Contrast Autostretch 1.06 --- image filter plug-in for The Gimp image
* manipulation program
*
* Copyright (C) 1996 Federico Mena Quintero
*
* You can contact me at quartic@polloux.fciencias.unam.mx
* 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.
*/
#include "config.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 c_astretch (GimpDrawable *drawable);
static void indexed_c_astretch (gint32 image_ID);
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_c_astretch",
"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 not work "
"that well.",
"Federico Mena Quintero",
"Federico Mena Quintero",
"1996",
N_("_Stretch Contrast"),
"RGB*, GRAY*, INDEXED*",
GIMP_PLUGIN,
G_N_ELEMENTS (args), 0,
args, NULL);
gimp_plugin_menu_register ("plug_in_c_astretch", "<Image>/Layer/Colors/Auto");
}
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;
GimpRunMode run_mode;
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 Contrast..."));
gimp_tile_cache_ntiles (2 * (drawable->width / gimp_tile_width () + 1));
c_astretch (drawable);
if (run_mode != GIMP_RUN_NONINTERACTIVE)
gimp_displays_flush ();
}
else if (gimp_drawable_is_indexed (drawable->drawable_id))
{
indexed_c_astretch (image_ID);
if (run_mode != GIMP_RUN_NONINTERACTIVE)
gimp_displays_flush ();
}
else
{
/* gimp_message ("c_astretch: 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);
}
static void
indexed_c_astretch (gint32 image_ID)
{
guchar *cmap;
gint ncols, i;
gint rhi = 0, ghi = 0, bhi = 0, rlo = 255, glo = 255, blo = 255;
cmap = gimp_image_get_colormap (image_ID, &ncols);
if (!cmap)
{
g_message (_("c_astretch: cmap was NULL! Quitting...\n"));
gimp_quit();
}
for (i = 0; i < ncols; i++)
{
if (cmap[i * 3 + 0] > rhi) rhi = cmap[i * 3 + 0];
if (cmap[i * 3 + 1] > ghi) ghi = cmap[i * 3 + 1];
if (cmap[i * 3 + 2] > bhi) bhi = cmap[i * 3 + 2];
if (cmap[i * 3 + 0] < rlo) rlo = cmap[i * 3 + 0];
if (cmap[i * 3 + 1] < glo) glo = cmap[i * 3 + 1];
if (cmap[i * 3 + 2] < blo) blo = cmap[i * 3 + 2];
}
for (i = 0; i < ncols; i++)
{
if (rhi != rlo)
cmap[i * 3 + 0] = (255 * (cmap[i * 3 + 0] - rlo)) / (rhi - rlo);
if (ghi != glo)
cmap[i * 3 + 1] = (255 * (cmap[i * 3 + 1] - glo)) / (ghi - glo);
if (rhi != rlo)
cmap[i * 3 + 2] = (255 * (cmap[i * 3 + 2] - blo)) / (bhi - blo);
}
gimp_image_set_colormap (image_ID, cmap, ncols);
}
typedef struct {
gint alpha;
guchar lut[256][3];
guchar min[3];
guchar max[3];
gboolean has_alpha;
} AutoStretchParam_t;
static void
find_min_max (const guchar *src,
gint bpp,
gpointer data)
{
AutoStretchParam_t *param = data;
gint b;
for (b = 0; b < param->alpha; b++)
{
if (!param->has_alpha || src[param->alpha])
{
if (src[b] < param->min[b])
param->min[b] = src[b];
if (src[b] > param->max[b])
param->max[b] = src[b];
}
}
}
static void
c_astretch_func (const guchar *src,
guchar *dest,
gint bpp,
gpointer data)
{
AutoStretchParam_t *param = data;
gint b;
for (b = 0; b < param->alpha; b++)
dest[b] = param->lut[src[b]][b];
if (param->has_alpha)
dest[param->alpha] = src[param->alpha];
}
static void
c_astretch (GimpDrawable *drawable)
{
AutoStretchParam_t param;
gint b;
param.has_alpha = gimp_drawable_has_alpha (drawable->drawable_id);
param.alpha = (param.has_alpha) ? drawable->bpp - 1 : drawable->bpp;
/* Get minimum and maximum values for each channel */
param.min[0] = param.min[1] = param.min[2] = 255;
param.max[0] = param.max[1] = param.max[2] = 0;
gimp_rgn_iterate1 (drawable, 0 /* unused */, find_min_max, ¶m);
/* Calculate LUTs with stretched contrast */
for (b = 0; b < param.alpha; b++)
{
gint range = param.max[b] - param.min[b];
gint x;
if (range != 0)
for (x = param.min[b]; x <= param.max[b]; x++)
param.lut[x][b] = 255 * (x - param.min[b]) / range;
else
param.lut[param.min[b]][b] = param.min[b];
}
gimp_rgn_iterate2 (drawable, 0 /* unused */, c_astretch_func, ¶m);
}
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