M-Ary Phase Modulation for Digital Watermarking

Abstract

M-Ary Phase Modulation for Digital WatermarkingIn spread spectrum based watermarking schemes, it is a challenging task to embed multiple bits of information into the host signal.M-ary modulation has been proposed as an effective approach to multibit watermarking. It has been proved that anM-ary modulation based watermarking system outperforms significantly a binary modulation based watermarking system. However, in the existingM-ary modulation based algorithms, the value ofMis restricted to be less than 256, because asMincreases, the computation workload for data extraction advances exponentially. In this paper, we propose an efficientM-ary modulation scheme, i.e.,M-ary phase modulation, which reduces the computation in data extraction to a very low level. With this scheme, it is practical to implement anM-ary modulation based algorithm with a high value ofM, e.g.,M= 220. This is significant for a watermarking system, because it can either greatly increase the data capacity of a watermark given the necessary watermark robustness, or considerably improve the watermark robustness given the amount of information of the watermark. The superiority of the proposed scheme is verified by simulation results.