Rough set based effective technique of image watermarking

This paper presents rough set based image-adaptive reference watermarking technique based on Discrete Wavelet Transform (DWT) and Singular Value Decomposition (SVD). A novel method has been proposed through this paper for solving the problem of image ambiguity and statistically redundant wavelet coefficients occurs during removal of shift-invariance problem. To deal with these redundant wavelet coefficients, the concept of rough set based approximation set has been used for watermarking. Rough sets is a mathematical tool which provides an approach to approximate a given image matrix in approximation sets. Lower and upper approximation of wavelet sub-bands has been used to generate the reference image. This method is based on embedding the singular values of watermark image into singular values of rough sets based reference image. The proposed reference image watermarking algorithm provides better-quality watermarked image than other contemporary reference watermarking scheme while holding the robustness. (C) 2016 Elsevier B.V. All rights reserved.