You can do invisible digital watermarking that can survive quite a lot. There is a quick-and-easy commercial solution, Digimark, that's been built into the menu system of most of the image editors I've used over the last decade or so (all of them commercial products -- I haven't met a FOSS UI that I've been able to come to terms with yet). You'll be prompted to get an ID on your first use.
There are probably other, similar utilities available, and it's easy enough to home-grow a solution using the image math option and noisy, low-contrast text on a mid-grey background, but they don't have the benefit of making the sirens and whistles go off at a commercial print shop. There's not a lot you can do about digital reuse except to prove that the image is yours if you find somebody using your image.