This is a script that accepts either an image file from the user's computer, or a remote image on another server
(in that order), ensures it is less than 450px across or 600px down, resamples it down to those parameters if needed,
converts it to a JPEG, stores it on my server, and shows it to you. It demonstrates advanced capabilities such
as smart error messages and support for multiple image formats: JPEG, GIF, and PNG.