How to create and save an image from the specified url

<?
	/*
	* The code below creates and saves an image from the url specified. URL must return an image and should not be an html page. The __FILE__ is a PHP constant
	* and returns the absoulte path of current file
	*/
 
	$url="http://snapcasa.com/get.aspx?code=5348&size=l&url=http://www.yahoo.com";
	$contents=file_get_contents($url);
	$img=imagecreatefromstring($contents);
	$img_path=dirname(__FILE__)."/thumb.jpg"); 
	imagejpeg($img,$img_path);
 ?>