my $reference_image = new GD::Image(100,100);
my @colornames;
{
    my $goodline = qr/^\d/;
    open my $rgbdat, '<', '/usr/X11/lib/X11/rgb.txt'
            or die $!;
    while (<$rgbdat>) {
        /$goodline/ or next;
        my @dat = split " ", $_, 4;
        my $color = pop @dat;
        $colornames[getindex($reference_image, @dat)] = $color;
    }
    close $rgbdat or die $!;
}