Bi-Watermarking Algorithm Based on Contourlet

A bi-watermarking algorithm basing on Contourlet transform is proposed in this paper. The algorithm adopts different methods to insert watermark into the low frequency and high frequency of the host image respectively. Firstly, perform Contourlet transform to the host image, then choose the low frequency to embed the watermark combined with Singular Value Decomposition(SVD), finally, putting coefficients into one group with the same coordinate in each finest directional subband, selecting the coefficients with the richest texture from each group as the coefficients to embed watermark. Therefore, watermark can be embedded into significant region as well as highly textured region of the host image. The method makes full use of the advantages of the dual watermarking in different subbands to resist different attacks, so the robustness of the algorithm can be improved. Experimental results show that the proposed algorithm is invisibility and is very robust to many image attacks.