gimp/app/base/threshold.c

82 lines
2.1 KiB
C

/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <glib-object.h>
#include "base-types.h"
#include "pixel-region.h"
#include "threshold.h"
void
threshold (Threshold *tr,
PixelRegion *srcPR,
PixelRegion *destPR)
{
const guchar *src, *s;
guchar *dest, *d;
gboolean has_alpha;
gint alpha;
gint w, h, b;
gint value;
h = srcPR->h;
src = srcPR->data;
dest = destPR->data;
has_alpha = (srcPR->bytes == 2 || srcPR->bytes == 4);
alpha = has_alpha ? srcPR->bytes - 1 : srcPR->bytes;
while (h--)
{
w = srcPR->w;
s = src;
d = dest;
while (w--)
{
if (tr->color)
{
value = MAX (s[RED], s[GREEN]);
value = MAX (value, s[BLUE]);
value = (value >= tr->low_threshold &&
value <= tr->high_threshold ) ? 255 : 0;
}
else
{
value = (s[GRAY] >= tr->low_threshold &&
s[GRAY] <= tr->high_threshold) ? 255 : 0;
}
for (b = 0; b < alpha; b++)
d[b] = value;
if (has_alpha)
d[alpha] = s[alpha];
s += srcPR->bytes;
d += destPR->bytes;
}
src += srcPR->rowstride;
dest += destPR->rowstride;
}
}