sub rgb{ unpack 'N', pack 'xCCC', @_ }

##</code><code>##

#!/usr/bin/perl -slw
use strict;
use GD;

sub rgb{ unpack 'N', pack 'xCCC', @_ }

my $width = 800;
my $height = 600;
my $img = new GD::Image( $width, $height, 1 );

for my $x ( 0 .. $width -1 ) {
    for my $y ( 0 .. $height -1 ) {
        $img->setPixel( 
            $x, $y, rgb( $x * 255 / $width, $y * 255 / $height, 0 ) 
        );
    }
}

open my $fh, '>:raw', 'picture.png' or die "uh oh spaghettio : $!";
print $fh $img->png;
close $fh;

## display result on win32 systems
system 'picture.png';