Abstract: Aiming at the problem that the traditional color image watermarking algorithm usually only embeds a random signal or binary image into the color carrier image, by combining the advantages of chaotic system and Schur decomposition, a robust watermarking algorithm is proposed, which embeds a color watermarking image into a color cover image. Firstly, the Arnold scrambling and chaotic encryption are performed on the color watermarking image to improve the security performance of the color watermarking image. Secondly, the color cover image is separated into three channels, each channel is divided into 4×4 non-overlapping blocks, and Schur decomposition is done on the selected block. Finally, the pre-processed watermarking signal is embedded into the maximum energy element after Schur decomposition. The experimental results show that the proposed algorithm has better imperceptibility, and has better robustness to filter attacks, noise attacks, JPEG compression attacks, and multiple combined attacks. Compared with similar watermarking algorithms based on Schur decomposition, this algorithm has better anti-attack performance for most attacks.

Key words: digital watermarking, color image, Schur decomposition, chaotic scrambling, robustness