Robust watermarking with improved modified spread spectrum

This paper presents a robust approach for spread spectrum (SS) based watermarking process. Unlike the traditional SS or other improvements, this method can work properly in case of absence of watermark and achieve good performance. If the channel has no noise, the error probability of the new design is zero, which is not existed in almost SS-based watermarking systems. Based on analysis by theory, the optimal threshold is calculated. Moreover, the simulations are implemented to verify to the theory.