/*
  Sampe code uses JPEG and TIFF library.
  This program reads a jpeg image, processes it and output to a tiff image.
  It is tested on Linux 2.4.
  To compile: gcc -o jpeg2tiff jpeg2tiff.c -ljpeg -ltiff -lm
  
  JPEG library can be obtained from http://www.ijg.org
  TIFF library can be obtained from http://www.libtiff.org
*/

#include <stdio.h>

#include "tiffio.h"
#include "jpeglib.h"

unsigned char **cpicalloc( int row, int col) 
{
  int i;
  unsigned char **p;
  
  p = (unsigned char **) calloc(row,sizeof(unsigned char *));
  if(!p){
    fprintf(stderr,"memory allocation error\n");
    exit(1);
  }
  for(i=0;i<row;i++){
    p[i] = (unsigned char *) calloc(col,sizeof(unsigned char));
    if(!p[i]){
      fprintf(stderr,"memory allocation error\n");
      exit(1);
    }
  }
  return p;
}

main()
{
  char file_name[50];
  unsigned char **pic, **out_pic,*scan_line;
  int i, j;
  struct jpeg_decompress_struct cinfo;  
  struct jpeg_error_mgr jerr;
  int row_stride;
  FILE *jpegin;
  TIFF *tifout;

  sprintf(file_name, "%s.jpg", "testimg");
  if((jpegin = fopen(file_name, "rb")) == NULL){
    fprintf(stderr, "cannot open %s\n", file_name);
    return 0;
  }

  cinfo.err = jpeg_std_error(&jerr);                                   
  jpeg_create_decompress(&cinfo);
  jpeg_stdio_src(&cinfo, jpegin);
  (void) jpeg_read_header(&cinfo, TRUE);
  (void) jpeg_start_decompress(&cinfo);
  row_stride = cinfo.output_width * cinfo.output_components;

  pic = cpicalloc(cinfo.output_height, cinfo.output_width*3);                // Allocation for a color picture 
  out_pic = cpicalloc(cinfo.output_height, cinfo.output_width);              // Allocation for a B/W picture   


  while (cinfo.output_scanline < cinfo.output_height) {                      // read a jpeg picture file  
    (void) jpeg_read_scanlines(&cinfo, &pic[cinfo.output_scanline], 1);
  }

  (void) jpeg_finish_decompress(&cinfo);                                                  
  jpeg_destroy_decompress(&cinfo);
  fclose(jpegin);

  /* Simple Processing (Convert to B/W picture) */
  for(i=0; i<cinfo.output_height; i++)
    for(j=0; j<cinfo.output_width; j++)
      out_pic[i][j] = (unsigned char) ((double)pic[i][3*j]*0.13+ (double)pic[i][3*j+1]*0.62 + (double)pic[i][3*j+2]*0.25);    // convert to a B/W image (B*0.13+G*0.62+R*0.25)  
     

  sprintf(file_name, "%s.tif", "output");
  if((tifout = TIFFOpen(file_name, "w")) == NULL){
    fprintf(stderr, "tiff file open error.\n");
    exit(0);
  }

  TIFFSetField(tifout, TIFFTAG_IMAGEWIDTH, cinfo.output_width);             // Set fields of a TIFF file  
  TIFFSetField(tifout, TIFFTAG_IMAGELENGTH, cinfo.output_height);
  TIFFSetField(tifout, TIFFTAG_PLANARCONFIG, 1);                            // set storage organization to 1
  TIFFSetField(tifout, TIFFTAG_BITSPERSAMPLE, 8);                           // 8 bit pier pixel     
  TIFFSetField(tifout, TIFFTAG_SAMPLESPERPIXEL,1);                          // 1 channel per pixel 
  TIFFSetField(tifout, TIFFTAG_PHOTOMETRIC,1);
  // Writing to the output file 
  for(i=0; i<cinfo.output_height; i++)
     TIFFWriteScanline(tifout, out_pic[i], i, 0);    
 
  
  TIFFClose(tifout);

}