/*********************************************************/
/*   program 11: perform arithmetic point operation      */
/*********************************************************/

#define  XSIZE  640
#define  YSIZE  480

unsigned char *i1r,*i1g,*i1b;
unsigned char *i2r,*i2g,*i2b;
unsigned char *or,*og,*ob;

main()
  {
  long  int  x,y,i;
  unsigned char lut[256];

  /* allocate input and output memory buffers */
  i1r = (unsigned char *)malloc(XSIZE*YSIZE);
  i1g = (unsigned char *)malloc(XSIZE*YSIZE);
  i1b = (unsigned char *)malloc(XSIZE*YSIZE);
  i2r = (unsigned char *)malloc(XSIZE*YSIZE);
  i2g = (unsigned char *)malloc(XSIZE*YSIZE);
  i2b = (unsigned char *)malloc(XSIZE*YSIZE);
  or  = (unsigned char *)malloc(XSIZE*YSIZE);
  og  = (unsigned char *)malloc(XSIZE*YSIZE);
  ob  = (unsigned char *)malloc(XSIZE*YSIZE);

/* 
  Read the input images.
*/
  read_image("input1",i1r,i1g,i1b);
  read_image("input2",i2r,i2g,i2b);

/* 
  Perform the arithmetic operation
  note: this example adds to images together to reduce noise.
*/
  for (y = 0; y < YSIZE; y++)
    {
    for (x = 0; x < XSIZE; x++)
      {
      or[(y*XSIZE)+x] = (i1r[(y*XSIZE)+x] + i2r[(y*XSIZE)+x]) / 2;
      og[(y*XSIZE)+x] = (i1g[(y*XSIZE)+x] + i2g[(y*XSIZE)+x]) / 2;
      ob[(y*XSIZE)+x] = (i1b[(y*XSIZE)+x] + i2b[(y*XSIZE)+x]) / 2;
      }
    }

/* 
  Write the output image.
*/
  write_image("output",or,og,ob);

/* 
  Free memory buffers.
*/
  free(i1r);
  free(i1g);
  free(i1b);
  free(i2r);
  free(i2g);
  free(i2b);
  free(or);
  free(og);
  free(ob);
}