Intelligent perceptual shaping of a digital watermark: Exploiting Characteristics of human visual system

Abstract

In this paper, we present a method for developing a Genetic Perceptual Model (GPM) applicable to a watermarking system. The proposed technique exploits the characteristics of human visual system using a Genetic Programming (GP) approach. We employ a tradeoff between watermark robustness and imperce ptibility, as an optimization criterion in the GP search. The resultant GPM is a combination of frequency, luminance sensitivity and contrast masking, enabling us to shape the watermark according to the cover image. Our investigations have shown that the evolved GPM provides maximum allowable imperceptible alterations to the Discrete Cosine Transform coefficients of a cover image. Comparative studies in terms of watermark imperceptibility and bit correct ratio performance have been carried out. The performance of the GPM has been analyzed for various watermarking schemes.