#! perl -slw
use strict;
use GD;

GD::Image->trueColor( 1 );

my $img1 = GD::Image->new( $ARGV[ 0 ] );
my $img2 = GD::Image->new( $ARGV[ 1 ] );

die "Different dimensions"
    unless $img1->width  == $img2->width
    and    $img1->height == $img2->height;

my $raw1 = $img1->gd;
my $raw2 = $img2->gd;

if( $raw1 ne $raw2 ) {
    print "images are different";
    printf "Process pixels? "; <STDIN>;

    for my $y ( 0 .. $img1->height -1 ) {
        for my $x ( 0 .. $img1->width -1 ) {
            my $p1 = $img1->getPixel( $x, $y );
            my $p2 = $img2->getPixel( $x, $y );
            if( $p1 != $p2 ) {
                print "Difference at ($x:$y): [@{[ $img1->rgb( $p1 ) ]}]  .v. [@{[ $img2->rgb( $p2 ) ]}]";
            }
        }
    }
}
else {
    print "Images are the same";
}
__END__