Right, kawecki. I did a search on invisible watermarking - after eating. ;) Yes, they do use 'something insignificant': the least-significant bit of the RGB. The image must be in RGB format for this to work (as compared to GIF/IFF with a lookup table). But, as you say, it is still possible to remove this. So you either have an easily removable, undetectable watermark or a gaudily visible one that is difficult to remove. No way to win. I agree with the idea of retaining a safely stored original that cannot be reproduced by an impersonator. For instance, I can quite easily prove in any court that I am the creator of one of my DVD sets since I have all of the original video (cuts and all), files, references, and so on. Someone would need to break into my house and steal almost everything I own to prove otherwise. ;)

C makes it easy to shoot yourself in the foot. C++ makes it harder, but when you do, you blow your whole leg off.

 -- Bjarne Stroustrup

Contact Me | Kuroyume's DevelopmentZone