#define grey_width 16
#define grey_height 16
static char grey_bits[] = {
   0x55, 0x55, 0xaa, 0xaa, 0x55, 0x55, 0xaa, 0xaa, 0x55, 0x55, 0xaa, 0xaa,
   0x55, 0x55, 0xaa, 0xaa, 0x55, 0x55, 0xaa, 0xaa, 0x55, 0x55, 0xaa, 0xaa,
   0x55, 0x55, 0xaa, 0xaa, 0x55, 0x55, 0xaa, 0xaa};