A new robust semi blind watermarking using block DCT and SVD

In this paper, a new semi blind robust gray scale watermarking algorithm based on block DCT and SVD is proposed. The watermark signal is (64×64×8) bit gray image. First, the original image is divided into blocks according to the size of the watermark; each block corresponds to each pixel value of watermark. Second, the block DCT is applied in each block once and form new blocks. The first pixel value of each block is collected together to form a new matrix. Apply SVD on the new matrix again to get the S matrix. The pixel value of watermark is embedded into the new S matrix through some method. The watermark can be detected with the original image. The experimental results show that the algorithm can satisfy the transparence and robustness of the watermarking system to a greater extent. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks very well.