Trust me to have a unique problem..OK - most of the stuff I do needs to be saved in png format. My sources can be any other, but usually jpeg or BMP. I do the work, keep a save file in PNT format and when I am done, I save the final file as PNG. I am not sure what more I can tell you about it? Not all have layers, not all are complex..sometimes it is simply a case of getting the original, opening it and then and resaving it to PNG. How specific do you want me to be? The BMP files are almost always created by UVMapper, the others, jpeg and gif etc come from all over...