Thumbnail Generator

<?php
$image = $_GET['image'];

$regex = '#([a-zA-Z0-9]+)_thumb\.(png|jpe?g|gif)$#';

preg_match($regex, $image, $matches);

unset($image);
unset($regex);

$directory = '/home/user/public_html/images';
$image = sprintf("%s/%s.%s", $directory, $matches[1], $matches[2]);

if(file_exists($image)) {
    $thumb = sprintf("%s/%s_thumb.%s", $directory, $matches[1], $matches[2]);
    shell_exec(sprintf("convert -interlace line -quality 80 -size 220x220 %s -resize 220 -profile '*' %s", $image, $thumb));
        echo 'Image Created Successfully!';
} else {
    header("Status: 404 Not Found");
}