use strict;
use warnings;
use GD::Simple;
use MCE::Map;

my $png = GD::Image->newFromPng('test.png');
my ($width,$height) = $png->getBounds;

MCE::Map->init( max_workers => 4 );

my @sw = mce_map {
    my ($y,$str) = ($_,'');
    for my $x (0..$width - 1) {
        $str .= getPixel($x,$y);
    }
    $str;
} 0..$height - 1;

MCE::Map->finish();

# print $_, "\n" for @sw;

sub getPixel {
    my ($index)   = $png->getPixel($_[0],$_[1]);
    my ($r,$g,$b) = $png->rgb($index);
    my $p = ($b > 128 || $r > 128) ? 0 : 1;
    return $p;
}