基于SIFT的NSCT-SVD域水印算法

提出一种利用尺度不变特征变换（SIFT）关键点对图像几何校正的非抽样Contourlet变换-奇异值分解域（NSCT-SVD）彩色图像水印算法。该算法利用蓝色与绿色分量的NSCT域低频子块的最大奇异值的关系，在蓝色分量上嵌入经过混沌加密的水印信息。水印检测时，先利用红色分量NSCT域低频系数上匹配的SIFT关键点信息对被检测图像进行几何攻击校正，恢复了水印的同步信息后再提取水印。实验结果表明，该算法对于噪声、滤波、压缩以及各类几何攻击具有较好的鲁棒性。

Color image watermarking algorithm in NSCT-SVD based on SIFT

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 sub-blocks between gray and blue components, and embeds the watermark into the blue component, which has been en-crypted by chaos system. During the watermarking detection, using the stable SIFT keypoints of the NSCT low-fre-quency in red component to correct the geometric attacks in the watermarked image, the watermark synchronous in- formation is recovered and the watermark is extracted. Experimental results show that the proposed scheme is ro-bust to a wide range of image processing operations such as adding noise, filtering and compression and all kinds of geometric attacks.