Require PHP>=5.5.0だしテストもしてない

get_minecraft_skinface.php

<?php

$user = "$_GET['user']";
$url = "http://s3.amazonaws.com/MinecraftSkins/{$user}.png";
$src = imagecreatefrompng(file_get_contents($url));

$face = imagecrop($src, ['x' => 8, 'y' => 8, 'width' => 8, 'height' => 8]);

header('Content-Type: image/png');
imagepng($face);