Thumbnail generator using PHP

thumbgenerator.php

<?php

function CreateThumb($file, $photo_url) {

	$square_size = 160;
	$quality = 100;
	
	//GET THE SOURCE IMAGE'S METADATA
	if($photo_url!="") list($width, $height, $type, $attr) = getimagesize($photo_url);

	//CHECK SOURCE IMAGE'S DIMENSION
	if($width>$height) {
		$width_t = $square_size;
		//ADJUST THE RATIO OF THE THUMBNAIL
		$height_t = round($height/$width*$square_size);
		
		//SET THE OFFSET SO THE IMAGE IS PLACED IN THE CENTER OF THE THUMBNAIL
		$off_y = ceil(($width_t-$height_t)/2);
		$off_x = 0;
		
	} elseif($height>$width) {
		$height_t = $square_size;
		$width_t = round($width/$height*$square_size);
		$off_x = ceil(($height_t-$width_t)/2);
		$off_y = 0;
		
	} else {
		$width_t = $height_t = $square_size;
		$off_x = $off_y = 0;
	}

	//GET THE PIXELS OF THE ORIGINAL IMAGE
	$thumb = imagecreatefromjpeg($photo_url);
	
	$thumb_p = imagecreatetruecolor($square_size, $square_size);
	
	//SET THE BACKGROUND TO BLACK
	$bg = imagecolorallocate($thumb_p, 0, 0, 0);

	//REDRAW THE IMAGE
	imagefill($thumb_p, 0, 0, $bg);
	imagecopyresampled($thumb_p, $thumb, $off_x, $off_y, 0, 0, $width_t, $height_t, $width, $height);
	
	//CREATE THE THUMBNAIL FILE
	imagejpeg($thumb_p, "thumb_".$file.".jpg", $quality);

	//CLEAN UP
	imagedestroy($thumb_p);
    	imagedestroy($thumb);

}