A blind watermarking algorithm based on adaptive quantization in Contourlet domain

Aiming at the copyright protection of digital works, a blind watermarking algorithm in Contourlet domain based on adaptive quantization is proposed. The algorithm adaptively regulates quantization step size in the Contourlet domain according to the mean of each sub block, so that the embedding strength of watermark can better adapt to the characteristics of each sub block. Before extracting watermark, the rotation correction algorithm has been applied in processing image, which greatly improves the ability of blind watermarking algorithm to resist rotation attacks. Many anti attack experiments are carried out on the proposed algorithm. The results show that the algorithm has good robustness, and it has distinctness advantages in anti JPEG compression, Gauss noise, shear and rotation attack.