The latest version of ionForge's Evolution source control software includes a graphics differencing tool which allows you to see the changes that have been made to successive versions of an image or changes caused when altering image compression or file type. This new feature is unique to Evolution. If you want to check it out, there is more info on the ionForge website (http://www.ionforge.com/news.html?news_item=9/?code=248867
). ionForge also offers a free, single-user, [b]perpetual[/b] license for Evolution which is available for anyone to download.