[PRODIG] TIFF/JPEG to RAW?

[Simon Brown]

While discussing the pros and cons of digital with my wife the subject of competitions arose. When entering a competition digital submissions in TIFF or JPEG  normally have to be backed up by their original RAW file, but lets say you shot a wonderful image in TIFF or JPEG but then needed a RAW file........Is it possible to reverse the image creation process?   Just a theoretical question but one I could not answer!   Regards   Simon (Underwater) Brown