Consideration of A Robust Watermarking Algorithm for Color Image Using Improved QR Decomposition

Abstract

In order to protect the color image copyright protection of the digital multimedia, it is necessary to design a color image watermarking algorithm. To achieve this purpose, an improved color image watermarking scheme based on QR decomposition for color image matrix is proposed in this paper. The proposed method gives a new algorithm to find elements of Q and R matrices instead of using Gram-Schmidt algorithm for QR factorization. First, R matrix is performed by solving a set of linear equations where diagonal elements of R are checked and modified if they are zero or negative. After that, Q matrix is computed based on R matrix. In addition, a novel formula is proposed to improve extracting time where the first element R(1,1) of R matrix is found instead of computing QR decomposition as the previous proposals. Experimental results show that the proposed method outperforms other methods considered in this paper in term of the quality of the watermarked images and the robustness of embedding method. Furthermore, the execution time is significantly improved and the watermark image is more robust under some tested attacks.