Thanks for the link Margaret.
I looked into digital watermarks during the discussion we had on
how to protect images. I was disappointed to discover that if a filter (just about any filter) is run on a digitally watermarked image, it essentially disables the watermark. Cropping a little bit keeps it, cropping a lot disables it.
Bottom line, the digital watermark helps you track in image that is copied as is. But, if someone wants to make "photo-art" from it and claim it as their own, it is pretty much impossible to track that.
Jeanie