Digital watermarking algorithm based on hyperchaos and fractional Fourier transform

In this paper, a novel digital image watermarking algorithm is proposed based on the hyperchaos system and fractional Fourier transform (FRFT) for copyright protection. The method making use of hyperchaotic key sequence to weak the correlation among the pixels of the watermark, in order to reinforce the security of the watermarking, and the watermark is also encrypted in the FRFT transform domain. Furthermore, this paper proposes an improved embedding scheme, in which the encrypted watermarking is embedded into the middle frequency of the original image with different strength. Simulations under several conditions are performed to verify the effectiveness of the proposed method, and the results show that the proposed algorithm is quite robust under either non-geometry or geometry attacks.