关键词: 数字水印, 非抽样Contourlet变换（NSCT）, 奇异值分解域（SVD）, 尺度不变特征变换（SIFT）, 鲁棒性

Abstract: A color image watermarking algorithm is presented which is in non-subsampled contourlet transform and singular value decomposition（NSCT-SVD）, by using scale-invariant features transform（SIFT） keypoints for image geometric correction. The algorithm uses the relations of the largest singular values of the NSCT low-frequency subblocks between gray and blue components, and embeds the watermark into the blue component, which has been encrypted by chaos system. During the watermarking detection, using the stable SIFT keypoints of the NSCT low-frequency in red component to correct the geometric attacks in the watermarked image, the watermark synchronous information is recovered and the watermark is extracted. Experimental results show that the proposed scheme is robust to a wide range of image processing operations such as adding noise, filtering and compression and all kinds of geometric attacks.

Key words: digital watermarking, Non-Subsampled Contourlet Transform（NSCT）, Singular Value Decomposition（SVD）, Scale-Invariant Features Transform（SIFT）, robustness