<?php require 'CImage.php'; // Give original file to the class constructor $img = new CImage('original.jpg'); // Define thumbnail file $img->setThumbnail('/tmp/scaled.png'); // Define thumbnail format. If this is not given, then the // output file will be in JPEG-format. $img->setFormat('png'); // If there is already file what is set in setThumbnail, then // this will define that we must overwrite file. Otherwise // if file exists, it will throw Exception $img->setOverwrite(true); // And now, resize to 500x200, but keep aspect ratio. // If you want excatly 500x200, then use this without third parameter. $img->resize('500', '200', 'FIT');