Does anyone know how to invisibly watermark a .jgp or is that even possible?
Just put your name and/or URL in small but unobtrusive text in the corner. That’s what I do and it doesn’t seem to uglify up the picture that much. I do think Photoshop may have some watermark feature (or at least they did) called Digimarc, but it was a hassle to use (last I tried).
I use one but admit I can’t even see it even when I am in the software itself which surprised me. Mine is an older one but do a search and you can find something. Here are two:
I have occasionally used GIMP to create a watermark, by making a small logo and then using the software to make it almost transparent and overlaying it into a suitable position on the image. GIMP is an open-source image manipulator/creator, and is free (unlike expensive PhotoShop).