Cocktail watermarking on images

A novel image protection scheme called “cocktail watermarking” is proposed in this paper. We analyze and point out the inadequacy of the modulation techniques commonly used in ordinary spread spectrum watermarking methods and the visual model-based ones. To resolve this inadequacy, two watermarks which play complementary roles are simultaneously embedded into a host image. The new watermarking scheme has the characterictic that, no matter what an attack is, at least one watermark typically survives well. We also conduct a statistical analysis to derive the lower bound of the worst percentage for the likelihood that the better watermark (of the two) can be extracted. With this “high” lower bound, it is ensured that a “better” extracted watermark is always obtained. Results of extensive experiments indicate that our cocktail watermarking scheme is remarkably effective in resisting various attacks.