use strict;
use warnings;
use feature 'say';
use GD;

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

GD::Image-> trueColor( 1 );

my $i = GD::Image-> new( 8, 8 );
$i-> filledRectangle( 0, 0, 7, 7 ,$i-> colorAllocate( 255, 0, 0 ));

my @ok_methods;

for my $m ( 1 .. 30 ) {
    eval {
        for my $w ( 1 .. 7 ) {
            $i-> interpolationMethod( $m );
            my $j = $i-> copyScaleInterpolated( $w, $w );

            for my $y ( 0 .. $w - 1 ) {
                for my $x ( 0 .. $w - 1 ) {
                    my ( $r ) = $j-> rgb( $j-> getPixel( $x, $y ));
                    die unless 255 == $r;
                }
            }
        }
        1;
    } or next;
    push @ok_methods, $m;
}

say 'looks like ok methods are: ', join ' ', @ok_methods;

__END__

v5.38.0
2.78
2.3.2
looks like ok methods are: 1 2 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20