Which image formats and types should be in testing packet?

Question

I want to create free image pack to help QA testers with testing applications, which use graphics avatars and other support images for main content (like images for user text records and so). Can anybody give links to exsisting testers' image packs?

I also need information and articles about image formats. I want to include vector and pixel images with different formats (JPEG, PNG, XPM, SVG), but which types of images exist? Which colormaps may be used, which layers and canals (alpha transparency etc...), additional information with images: EXIF, metadata.

Thanks for your answers.