A Blind Watermarking Algorithm for Digital Image

Based on the method of SVD, a novel watermark algorithm is designed in this paper. Firstly, the SVD is performed on each segment of the original host image; Secondly, the watermark bits are formed by chaotic encrypting;Thirdly, the secret bits are embedded into the S component of the matrix by quantization; Lastly, the inverse SVD transformation is performed on each block and the watermarked image is constructed. The original host image is not required in the secret watermark recovery. Experimental results show that the watermarked image has transparent feature, and the quality of the recovered watermark is satisfying. The algorithm is strongly robust to many attacks, such as JPEG compression attack, Noise Interference and so on..