Are perfect image watermarking schemes possible?

We propose mathematical performance measures by which the robustness, imperceptibility and information content of various watermarking methods could be measured. These measures rely in the notion of equivalence in the perceptual domain and some basic information-theoretic concepts. Based on these measures we show that the success of image watermarking heavily depend on the functional form of the human visual system perceptual mask. We also analyse the implication for robust watermarking of some commonly used perceptual masks.