gd_nnquant.h

/* maximum number of colours that can be used.
  actual number is now passed to initcolors */
#define MAXNETSIZE 256
 
/* For 256 colours, fixed arrays need 8kb, plus space for the image
   ---------------------------------------------------------------- */
 
/* four primes near 500 - assume no image has a length so large */
/* that it is divisible by all four primes */
#define prime1 499
#define prime2 491
#define prime3 487
#define prime4 503
 
#define minpicturebytes (4 * prime4) /* minimum size for input image */