Informed embedding: exploiting image and detector information during watermark insertion

Usually watermark embedding simply adds a globally or locally attenuated watermark pattern to the cover data (photograph, music, movie). The attenuation is required to maintain fidelity of the cover data to an observer while the watermark detector considers the cover data to be "noise". We refer to this as blind embedding. Cox, Miller and McKellips (see Proceedings of the IEEE, vol.87, no.7, p.1127-41, 1999) observed that the cover data is not noise, i.e. it is not random but completely known at the time of embedding. This knowledge, along with knowledge of the detection algorithm to be used, allows a new category of informed embedder to be realized. We describe a simple watermarking algorithm and then compare the performance of blind embedding with three types of informed embedding. Note that in all four cases, the watermark detector is unchanged, only the embedder is altered. Experimental results clearly reveal the improvement of informed over blind embedding.