A Novel Grayscale Watermarking Algorithm

In this paper,a novel grayscale watermarking algorithm based on Two-Level Discrete Cosine Transform (DCT) and Singular Value Decomposition (SVD) is proposed. The watermark signal is (32 × 32 × 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 DCT is applied in each block twice and form new blocks.Then,perform SVD on each new block to get matrices U,S and V for each block.The pixel value of watermark is embedded into the largest singular value of S matrix of each new block.And 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 very well. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks.