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/* Hack for grayscaling an image */
/*
* Copyright (C) 2002 Red Hat Inc.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <gdk-pixbuf/gdk-pixbuf.h>
#include <unistd.h>
#include <stdlib.h>
#include <math.h>
#define INTENSITY(r, g, b) ((r) * 0.30 + (g) * 0.59 + (b) * 0.11)
static GdkPixbuf*
grayscale_pixbuf (GdkPixbuf *pixbuf)
{
GdkPixbuf *gray;
guchar *pixels;
int rowstride;
int pixstride;
int row;
int n_rows;
int width;
gray = gdk_pixbuf_copy (pixbuf);
rowstride = gdk_pixbuf_get_rowstride (gray);
pixstride = gdk_pixbuf_get_has_alpha (gray) ? 4 : 3;
pixels = gdk_pixbuf_get_pixels (gray);
n_rows = gdk_pixbuf_get_height (gray);
width = gdk_pixbuf_get_width (gray);
row = 0;
while (row < n_rows)
{
guchar *p = pixels + row * rowstride;
guchar *end = p + (pixstride * width);
while (p != end)
{
double v = INTENSITY (p[0], p[1], p[2]);
p[0] = (guchar) v;
p[1] = (guchar) v;
p[2] = (guchar) v;
p += pixstride;
}
++row;
}
return gray;
}
int
main (int argc, char **argv)
{
GdkPixbuf *pixbuf;
GdkPixbuf *gray;
GError *err;
if (argc != 2)
{
g_printerr ("specify a single image on the command line\n");
return 1;
}
g_type_init ();
err = NULL;
pixbuf = gdk_pixbuf_new_from_file (argv[1], &err);
if (err != NULL)
{
g_printerr ("failed to load image: %s\n", err->message);
g_error_free (err);
return 1;
}
gray = grayscale_pixbuf (pixbuf);
err = NULL;
gdk_pixbuf_save (gray, "grayscale.png", "png", &err, NULL);
if (err != NULL)
{
g_printerr ("failed to save image: %s\n", err->message);
g_error_free (err);
return 1;
}
g_print ("wrote grayscale.png\n");
return 0;
}
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