Accurate watermarking capacity evaluation

Defined as the maximum amount of information which can be inserted in an original media for prescribed transparency and robustness, watermarking capacity has been a challenging research topic in the last years. The present paper allows several current limitations in this respect to be overcame. As the capacity strongly depends on the attack statistical behaviour, the first part of our paper is devoted to their in-depth investigation. By advancing an original statistical approach, it is pointed out that we may speak about probability density functions modelling several types of attacks (filtering, small rotation, StirMark). Then, these new accurate models are considered as the starting points in the probability evaluation. The experimental study is based on the watermarking methods inserting the mark in the hierarchy of the coefficients corresponding to three types of wavelets transforms, namely the (2,2), (4,4) and (9,7). The video corpus consisted in 10 video sequences of about 25 minutes each, with heterogeneous content.