1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
#include <stdio.h>
#include <stdlib.h>
/* jpeg includes */
/* Note that jpeglib.h also requires jconfig.h and jmorecfg.h to be
in the same directory as jpeglib.h */
#include <jpeglib.h>
extern JSAMPLE * image_buffer; /* Points to large array of R,G,B-order data */
int image_height; /* Number of rows in image */
int image_width; /* Number of columns in image */
int image_quality; /* Compression Quality */
FILE *out;
extern void write_JPEG_file (JSAMPLE *scan, FILE *out)
{
extern int image_width, image_height, image_quality;
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
JSAMPROW row_pointer[1]; /* pointer to JSAMPLE row[s] */
int row_stride; /* physical row width in image buffer */
cinfo.err = jpeg_std_error(&jerr);
/* Now we can initialize the JPEG compression object. */
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, out);
cinfo.image_width = image_width; /* image width and height, in pixels */
cinfo.image_height = image_height;
cinfo.input_components = 1; /* # of color components per pixel */
cinfo.in_color_space = JCS_GRAYSCALE; /* colorspace of input image */
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, image_quality, TRUE /* limit to baseline-JPEG values */);
jpeg_start_compress(&cinfo, TRUE);
row_stride = cinfo.input_components*image_width; /* JSAMPLEs per row in image_buffer */
while (cinfo.next_scanline < cinfo.image_height) {
/* jpeg_write_scanlines expects an array of pointers to scanlines.
* Here the array is only one element long, but you could pass
* more than one scanline at a time if that's more convenient.
*/
row_pointer[0] = & scan[cinfo.next_scanline * row_stride];
(void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
}
|
