the wrapper.php works with every image and on every webserver.
you can adjust the location of the wrapper.php in the .htaccess file.
my only concern about is, that the image quality decreases after rendering with the watermark. I don't know where to check to improve the image quality after "watermarking".
I tried to ask the developer (http://www.jumpx.com/tutorials/wrapper
) but didn't get any answer.