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/****************************************************************************
jpeg.c - read and write jpeg images using libjpeg routines
Copyright (C) 2002 Hari Nair <hari@alumni.caltech.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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <jpeglib.h>
int
read_jpeg(const char *filename, int *width, int *height, unsigned char **rgb)
{
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
unsigned char *ptr = NULL;
unsigned int i, ipos;
FILE *infile = fopen(filename, "rb");
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
*width = cinfo.output_width;
*height = cinfo.output_height;
rgb[0] = malloc(3 * cinfo.output_width * cinfo.output_height);
if (rgb[0] == NULL)
{
fprintf(stderr, "Can't allocate memory for JPEG file.\n");
fclose(infile);
return(0);
}
if (cinfo.output_components == 3)
{
ptr = rgb[0];
while (cinfo.output_scanline < cinfo.output_height)
{
jpeg_read_scanlines(&cinfo, &ptr, 1);
ptr += 3 * cinfo.output_width;
}
}
else if (cinfo.output_components == 1)
{
ptr = malloc(cinfo.output_width);
if (ptr == NULL)
{
fprintf(stderr, "Can't allocate memory for JPEG file.\n");
fclose(infile);
return(0);
}
ipos = 0;
while (cinfo.output_scanline < cinfo.output_height)
{
jpeg_read_scanlines(&cinfo, &ptr, 1);
for (i = 0; i < cinfo.output_width; i++)
{
memset(rgb[0] + ipos, ptr[i], 3);
ipos += 3;
}
}
free(ptr);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(infile);
return(1);
}
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