PHP Simple Image Crop

<?php 

$x = $CropXStart; // Crop Start X position in original image
$y = $CropYStart; // Crop Srart Y position in original image

$w = abs($CropXEnd - $CropXStart); // Thumb width
$h = abs($CropYEnd - $CropYStart); // Thumb height

$image = imagecreatefromjpeg($source); 
$crop = imagecreatetruecolor($w,$h);

imagecopy ($crop, $image, 0, 0, $x, $y, $w, $h );
imagejpeg($crop, 'cropped.jpg', 100);
?>