Digital watermarking based on stochastic resonance signal processor

Abstract

A signal processor based on an bi-stable aperiodic stochastic resonance (ASR) is introduced firstly. The processor can detect the base-band binary pulse amplitude modulation (PAM) signal. A digital image watermarking algorithm in the discrete cosine transform (DCT) domain is implemented based on the processor. In this algorithm, the watermark and the DCT alternating current (ac) coefficients of the image are viewed as the input signal and the channel noise of the processor input, respectively. In conventional watermarking systems, it's difficult to explain why the detection bit error ratio (BER) of a watermarking system suffering from some kinds of attacks is lower than that of the system suffering from no attack. In the present watermarking algorithm, this phenomenon is systematically analyzed. It is shown that the DCT ac coefficients of the image as well as the noise imported by the attacks will cooperate within the bi-stable ASR system to improve the performance of the watermark detection. © Springer-Verlag Berlin Heidelberg 2007.