" The problem is that an invisible watermark only works if someone is being very careless and not doing anything to find and circumvent such measures. I can think of several easy ways to remove the watermark, none of them very technical even:" "1. If the image is high-resolution, print it and scan it back. No more invisible watermark." Probably it will work, I'm not sure. "2. Display and take a screenshot. Even for an image with resolution larger than the screen, several screenshots can easily be reconstructed in PS or PSP." It will not work, watermark will be preserved. "3. Convert in some application to another format that drops the watermark data." It will not work, watermark will be preserved. Watermark are distributed in all the image, a fragment of the image contains the watermark. Watermarks are the same as holograms and are based on the same principle. Watermark are done in the frecuency or wavelet domain and not in the spatial domain. But watermarks can be easily removed by some softwares or simple PaintShop operations.

Stupidity also evolves!