If you don't want your art stolen, then the only "protection" is to place a watermark layer on the image. Make it faint, of course, but have it run through the core part of the image. If you make it very very faint, everyone can still enjoy the image, and you can be sure the thieves will not want to use it as a SHOW piece. They may still claim the image (and having put the watermark there to protect "THEIR" iamge), but it will keep many from posting them in other forums. Other than that, you are screwed. It you try to embed digital signiture type information inside the binary information of the file, thieves can still bypass this by taking a snapshot of the whole screen and editing it out in Photoshop. Instant picture, no digital signature.