Abstract:

Aiming at the issues that robustness and security of most image watermarking are not strong，a digital watermarking algorithm based on multifactor encryption and Contourlet transform is proposed. Using the good pseudo randomness and mathematical statistical characteristics and the advantages of simple and quickly generated sequences of Chebyshev map, three chaotic sequences are produced. Two of them are used to encrypt the watermarking image, the left one is used as watermarking embedded keys; The Contourlet Transform is used to extract the subband coefficients of the original carrier and the encrypted watermark, then the coefficients of the watermark is embedded into the coefficients of the original carrier, thus accomplishing the watermark embedding process. The method is implemented and experiments are performed to compare the proposed method with other methods in literatures. The result shows that the algorithm owns better effect on robustness, security and invisibility.    

Key words: digital watermark;chaotic encryption;Chebyshev mapping;Contourlet transform