An improved watermarking algorithm for color image using Schur decomposition

In order to protect the color image copyright protection of the multimedia big data, it is necessary to design a color image watermarking algorithm. To achieve this purpose, an improved color image watermarking algorithm based on Schur decomposition is proposed in this paper. First, the watermark information is, respectively, embedded into the upper triangular matrix and the unitary matrix of Schur decomposition by two different methods, and two temporary watermarked image blocks are obtained. Then, the proposed improved method is used to select the final watermarked image block from these temporary watermarked image blocks. The highlight of the proposed method is that the final watermarked block has less visual distortion. Meanwhile, the embedded flag is created and uploaded to the cloud service provider with the watermarked image. When extracting watermark, the original host image or the watermark image is not needed. Experimental results show that the proposed watermarking algorithm has better performance; in particular, the watermark invisibility has been obviously improved than other methods considered in this paper.