Watermarking security analysis based on information theory

This paper presents a theoretical analysis of security proposed by watermarking methods based on wavelet transform. In this paper, security is quantified from an information theory point of view via the equivocation and mutual information between parameters that must be kept secret and the parameters made publicly available by watermarker. The main idea is that the information theory tools are used to estimate the measure of information leakage for a variety of scenarios. Furthermore, the experimental results demonstrate the trade off between different properties of watermarking such as: security, robustness and imperceptibility. This analysis is applied to a multiresolution wavelet based watermarking technique which is named QSWT. The authors also search for parameters that consist of threshold value T and the number of QSWT coefficients to improve the visual quality of watermarked image and robustness of watermark.