Generalized Improved Spread Spectrum Robust Against Shifting Attacks

In this work, we considered the improvement of robustness of spread spectrum watermarking. For spread spectrum watermarking, interference between the host signal and the watermark reduce the performance of the system. In order to prevent this interference, improved spread spectrum method has been proposed, which modulates the amplitude of the watermark in order to decorrelate the host and watermark. This method improves the noise immunity, however it is still not robust against geometric attacks. The generalized improved spectrum method proposed in this paper reduce the correlation between the watermark and the host signal, not only on the part where the watermark is injected, but also in its neighborhood. Therefore, robustness against geometric attacks (in particular translation and shifting) is improved.