libjpeg

main.c

#include <stdio.h>
#include <stdlib.h>

#include <jpeglib.h>

unsigned char buf[3][64] = {{
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
	0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff,
	0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff,
	0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff,
	0x80, 0x00, 0x80, 0x80, 0x40, 0x40, 0x00, 0x40,
	0x80, 0x00, 0x80, 0x80, 0x40, 0x40, 0x00, 0x40,
	0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40,
	0x80, 0x80, 0x80, 0x80, 0x40, 0x40, 0x40, 0x40
},{
	0xff, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
	0x80, 0xff, 0xff, 0x80, 0x80, 0x80, 0x80, 0x80,
	0x40, 0xff, 0xff, 0x40, 0x40, 0x40, 0x40, 0x40,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
/* Padding */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
},{
	0xff, 0x80, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
	0xff, 0x80, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
	0xff, 0x80, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
	0xff, 0x80, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
/* Padding */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
}};
JSAMPARRAY jimage[3];

int main(int argc, char** argv) {
	struct jpeg_compress_struct cinfo;
	struct jpeg_error_mgr jerr;
	
	cinfo.err = jpeg_std_error(&jerr);
	jpeg_create_compress(&cinfo);

	cinfo.image_width = 8;
	cinfo.image_height = 8;
	cinfo.input_components = 3;
	jpeg_set_defaults(&cinfo);
	jpeg_set_colorspace(&cinfo, JCS_YCbCr);
	cinfo.raw_data_in = TRUE;
	cinfo.comp_info[0].h_samp_factor = 2;
	cinfo.comp_info[0].v_samp_factor = 2;
	cinfo.comp_info[1].h_samp_factor = 1;
	cinfo.comp_info[1].v_samp_factor = 1;
	cinfo.comp_info[2].h_samp_factor = 1;
	cinfo.comp_info[2].v_samp_factor = 1;
	jpeg_stdio_dest(&cinfo, stdout);
	jpeg_start_compress(&cinfo, TRUE);

	for(int i=0;i<cinfo.input_components;i++){
		jimage[i] = (JSAMPARRAY)calloc(cinfo.comp_info[i].height_in_blocks*DCTSIZE, sizeof(JSAMPROW));
		for(int j=0;j<cinfo.comp_info[i].height_in_blocks*DCTSIZE;++j) {
			jimage[i][j] = buf[i] + j * cinfo.comp_info[i].width_in_blocks*DCTSIZE;
		}
	}

	jpeg_write_raw_data(&cinfo,jimage,cinfo.max_v_samp_factor*DCTSIZE);
	
	for(int i=0;i<cinfo.input_components;i++){
		free(jimage[i]);
	}
	
	jpeg_finish_compress(&cinfo);
	jpeg_destroy_compress(&cinfo);

	return 0;
}