Png Transparence

<?php
function is404($filename)
{
    $handle = curl_init($filename);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
    $response = curl_exec($handle);
    $httpCode = curl_getinfo($handle, CURLINFO_HTTP_CODE);
    curl_close($handle);

    if ($httpCode >= 200 && $httpCode < 300)
	{
		return false;
    }
	else
	{
		return true;
    }
}
$pseudo = trim(@$_GET['pseudo']);
$filename = 'http://s3.amazonaws.com/MinecraftSkins/' . $pseudo . '.png';
if(is404($filename) || empty($pseudo))
{
	$filename = 'http://oxocraft.ch/launcheur/skins/' . $pseudo . '.png';
	if(is404($filename) || empty($pseudo))
	{
	$filename = 'http://s3.amazonaws.com/MinecraftSkins/char.png';
	}
}
header('Content-type: image/png');
$img1 = imagecreate(64, 32);
$img2 = imagecreatefrompng($filename);
imagepng($img2);
?>