So one of the key features in v5.0 of Code Collaborator is the ability to compare GIF, JPG, and PNG files. It works more or less the same way as comparing text files, with some important differences.
A big difference is that line numbers are of no use for tracking comments and defects in an image file. So Brandon came up with a push-pin user interface that records coordinates instead.
Another key difference is that Code Collaborator does not highlight the differences between two versions of an image file, like it does for text files. A more useful approach, it turns out, is to provide user interface controls that allow you to easily pick out the differences. So in addition to a typical side-by-side view of two versions of a file, the diff viewer also supports an over-under view.
When you use the over-under view with images, the image that was displayed on the right is on top. And initially it is partially transparent so that you can "see through" it to the image below it, which is the image that was on the left in the side-by-side view.
The really cool part is that you can alter the transparency with a slider control. The best way to understand all this is to watch it in action. Check out the video and then if you want to try it for yourself, download Code Collaborator v5.0.