Chaotic parameter modulation with application to digital watermarking

Digital watermarking is an enabling technology to prove ownership on copyrighted material, detect originators of illegally make copies, and monitor the usage of the copyrighted multimedia data. This paper presents a new technique for image watermarking based on analog spread spectrum system. The watermark is generated by the chaotic parameter modulation method. The copyright information is modulated into the initial condition of a chaotic system to generate a watermark signal. The retrieval of copyright information is then a problem of initial condition estimation from the corrupted watermark signal. Two efficient estimation techniques, namely, dynamical programming and halving method are applied to detect information from the corrupted watermarked image. It is shown that the new approach can modulate numerical information directly and outperforms the correlation-based spread spectrum watermarking spectrum.