/* getqtbl.c	Get the quantization table from a jpeg file and write it to
   a data file */

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

int main(int argc, char *argv[])
{
  /* variable declaration */
  register int i, j;
  
  FILE *JpgFile;			/* jpeg image file */
  FILE *QuanTableFile;			/* quantization table file */
  
  struct jpeg_decompress_struct dinfo;	/* jpeg decompression object */
  struct jpeg_error_mgr jerr;		/* jpeg error object */

  /* parse the command line */
  if (argc!=3) {
    fprintf(stderr, "Wrong number of command line arguments!\n");
    fprintf(stderr, "Usage: getqtbl jpeg_file quant_table_file\n");
    exit(1);
  }
  else {
    if ( !(JpgFile=fopen(argv[1], "rb")) ) {
      fprintf(stderr, "Can't open input jpeg file!\n");
      exit(1);
    }
    if ( !(QuanTableFile=fopen(argv[2], "wb")) ) {
      fprintf(stderr, "Can't open output quantization table file!\n");
      exit(1);
    }
  }

  /* allocate and initializing jpeg decompression object */
  dinfo.err = jpeg_std_error(&jerr);
  jpeg_create_decompress(&dinfo);

  /* specify data input source and read the header */
  jpeg_stdio_src(&dinfo, JpgFile);
  jpeg_read_header(&dinfo, TRUE);

  /* get the quantization table and write to a file */
  for (i=0;i<DCTSIZE2;i++)
    fputc((dinfo.quant_tbl_ptrs[0])->quantval[i], QuanTableFile);

  /* destory the jpeg object */
  jpeg_destroy_decompress(&dinfo);

  /* close all the files */
  fclose(JpgFile);
  fclose(QuanTableFile);

}