struct dither {
	char *name;
	char *altname;
	int xmask;
	int ymask;
	int nval;
	int mat[8][8];
} dithers[] = {
	"-block",
	"-bl",
	7,
	7,
	64,
{
	 8, 12, 36, 40, 10, 14, 38, 42, 
	 4,  0, 32, 44,  6,  2, 34, 46, 
	60, 48, 16, 20, 62, 50, 18, 22, 
	56, 52, 24, 28, 58, 54, 26, 30, 
	11, 15, 39, 43,  9, 13, 37, 41, 
	 7,  3, 35, 47,  5,  1, 33, 45, 
	63, 51, 19, 23, 61, 49, 17, 21, 
	59, 55, 27, 31, 57, 53, 25, 29
},

	"-halftone",
	"-h",
	7,
	7,
	64,
{
	52, 16, 44, 56, 54, 18, 46, 58, 
	40,  0,  4, 20, 42,  2,  6, 22, 
	28, 12,  8, 32, 30, 14, 10, 34, 
	48, 36, 24, 60, 50, 38, 26, 62, 
	55, 19, 47, 59, 53, 17, 45, 57, 
	43,  3,  7, 23, 41,  1,  5, 21, 
	31, 15, 11, 35, 29, 13,  9, 33, 
	51, 39, 27, 63, 49, 37, 25, 61
}
};