use strict;
use warnings;
use feature 'say';
use GD;
use Digest::MD5 'md5_hex';

say $^V; 
say $GD::VERSION;
say eval { GD::VERSION_STRING() } || '-';

GD::Image-> trueColor( 1 );

my $fn = 'CoventryCathedral.png';
my $i = GD::Image-> new( $fn );

use constant W => 100;

my $j = GD::Image-> new( W, W );

$j-> copyResampled( $i,
    0, 0,
    ( $i-> width - $i-> height ) * .5, 0,
    W, W, 
    $i-> height, $i-> height );

say eval { md5_hex( $j-> gd )} || '-';
say md5_hex( my_gd( $j ));

sub my_gd {             # same as gd() for truecolor images
    my $gd = shift;

    my ( $w, $h ) = $gd-> getBounds;
    my $s = '';
    for my $y ( 0 .. $h - 1 ) {
        for my $x ( 0 .. $w - 1 ) {
            $s .= pack 'L>', $gd-> getPixel( $x, $y );
        }
    }
    return "\xff\xfe" .
           ( pack 'S>2', $w, $h ) .
           "\1\xff\xff\xff\xff" .
           $s
}

__END__

v5.38.0
2.78
2.3.2
-
c97e63fc792ef75b5ff49c078046321e

v5.32.1
2.76
2.2.5
c97e63fc792ef75b5ff49c078046321e
c97e63fc792ef75b5ff49c078046321e

v5.24.3
2.66
2.1.1
adc191aea66fdf99fd74aaeb20b34e5e
adc191aea66fdf99fd74aaeb20b34e5e