class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
There must be something in the log. Output $handle->log after calling process()
Looking again at your code, it looks like you have your own custom process() function. In this function, you instantiate the class, but you didn't indicate whether you are calling the class' process() function.
Look again at the code examples in the doc. It should basically look like this:
$handle = new Upload($_FILES['custom_stationery']);
if ($handle->uploaded) $handle->process('/my/dest/dir/');
Looking again at your code, it looks like you have your own custom process() function. In this function, you instantiate the class, but you didn't indicate whether you are calling the class' process() function.
Look again at the code examples in the doc. It should basically look like this: