my $v = 0;
for (my $y = 0; $y < $IMAGE_BITS && ($y + $k * $IMAGE_BITS < $ch_height); ++$y) {
my $bit = ($bm[$k * $IMAGE_BITS + $y][int($x / $IMAGE_BITS)] & (1 << ($IMAGE_BITS - ($x % $IMAGE_BITS) - 1))) ? 1 : 0;
my $v = 0;
for (my $y = 0; $y < $IMAGE_BITS && ($y + $k * $IMAGE_BITS < $ch_height); ++$y) {
my $bit = ($bm[$k * $IMAGE_BITS + $y][int($x / $IMAGE_BITS)] & (1 << ($IMAGE_BITS - ($x % $IMAGE_BITS) - 1))) ? 1 : 0;