While I posted above my answer, what I didn't say was one commission I did for Brady Games Call of Duty: Advanced Warfare Strategy Guide of all their multi-player maps. The contract stated they needed layered PSD files, which had I created the original in Photoshop, then these would be the same as the source files. In actuality, I created the maps in Xara Designer Pro x11, whose file format is .XAR, but I sent what the publisher asked for by exporting to PSD format. This was the only exception to otherwise needing a JPG or PNG file. Of course, as stated, they didn't get the source files. And Brady Games did pay for that priviledge - and paid well.