Generalized improved spread spectrum watermarking robust against translation attacks

Abstract

In this work, we consider the ISS (improved spread spectrum) watermarking framework, and propose a generalized version of it, termed "generalized improved spread spectrum" (GISS), where we achieve both host-interference cancelation and robustness to "translation" attacks up to some tolerance. In particular, we reduce the correlation between the watermark and the host, not only at the embedding location, but also within an a-priori-de ned neigh- borhood around it. We show that the resulting framework leads to a constrained quadratic optimization problem, where the cost function and the constraint represent the amount of host interference on the watermark and the norm of the resulting "host interference cancelation sequence" (HICS), respectively. We provide a closed-form analytical solution to this optimization problem and experimentally demonstrate its e ectiveness for 1D signals. Also, we propose three di erent methods (search/correlation, joint MAP and focused MAP methods) for the decoding of embedded binary information and analyze the performances of these methods in terms of the probability of decoding error. Regarding these performances, we provide closed-form solutions for focused MAP and joint MAP detectors and experimental results of their performances. Moreover, for the search/correlation decoding method that we introduce, we provide analytical and experimental results regarding the performance.