PHP implements image scaling (experts have passed by)

PHP implements simple image scaling.

/**
 * The Images class is an image processing class
 * @author pan
 * @package application.controllers
 * @since 1.0
*/
class Images
{


 /**
 * Zoom image
 * @param $source original image
 * @param $newfile new image
 * @param $pre zoom ratio
*/
 public function thumn($source,$pre,$newfile)
 {
 //Get image size
 list($s_w,$s_h)=getimagesize($source);
 //Generate new image size
 $new_w=$s_w*$pre;
 $new_h=$s_h*$pre;

 //Create a new image
 $new_f=imagecreatetruecolor($new_w, $new_h);
 //Create an image with a resource image
 $sour_f=imagecreatefromjpeg($source);
 //Copy the resource image to a new image
 imagecopyresampled( $new_f, $sour_f, 0, 0, 0, 0, $new_w, $new_h, $s_w, $s_h);
 //Output the image to the browser
 imagejpeg($new_f,$newfile);

 imagedestroy($ new_f);
 imagedestroy($sour_f);
 }
}
 ?>