A Constructive and Unifying Framework for Zero-Bit Watermarking

In the watermark detection scenario, also known as zero-bit watermarking, a watermark, carrying no hidden message, is inserted in a piece of content. The watermark detector checks for the presence of this particular weak signal in received contents. The article looks at this problem from a classical detection theory point of view, but with side information enabled at the embedding side. This means that the watermark signal is a function of the host content. Our study is twofold. The first step is to design the best embedding function for a given detection function, and the best detection function for a given embedding function. This yields two conditions, which are mixed into one ´fundamental´ partial differential equation. It appears that many famous watermarking schemes are indeed solution to this ´fundamental´ equation. This study thus gives birth to a constructive framework unifying solutions, so far perceived as very different