Cascaded transform space watermarking based on analysis of local entropy variation

Abstract

Increasing multimedia content production and exchange has increased the need for better protection of copyright by means of watermarking. Different methods have been proposed to satisfy the tradeoff between imperceptibility and robustness as two important characteristics in watermarking while maintaining proper data-embedding capacity. Recently watermarking methods based on contourlet transform (CT) have demonstrated promising results. In this paper we have improved CT-based watermarking by overcoming some of previous methods' deficiencies. Our method cascades CT and Discrete Cosine Transform (DCT) to embed binary logos as watermark. Image blocks local entropy variations are used to adaptively control the strength factor of watermarking. This has enabled our method to take advantage of all image blocks to elevate the embedding capacity while preserving imperceptibility. Experimental results show the efficiency of the proposed method and better results comparing to similar works in this domain.