Error correction coding of nonlinear side-informed watermarking schemes

摘要

The application of error correction coding to side-informed watermarking utilizing polynomial detectors is investigated. The overall system is viewed as a code concatenation in which the outer code is a powerful channel code and the inner code is a low rate repetition code. For the inner code we adopt our previously proposed side-informed embedding scheme in which the watermark direction is set to the gradient of the detection function in order to reduce the effect of host signal interference. Turbo codes are employed as the outer code due to their near capacity performance. The overall rate of the concatenation is kept constant while parameters of the constituent codes are varied. For the inner code, the degree of non-linearity of the detector along with repetition rate is varied. For a given embedding and attack strength, we determine empirically the best rate combinations for constituent codes. The performance of the scheme is evaluated in terms of bit error rate when subjected to various attacks such as additive/multiplicative noise and scaling by a constant factor. We compare the performance of the proposed scheme to the Spread Transform Scalar Costa Scheme using the same rates when subjected to the same attacks.