DCT与SVD相融合的抗剪切攻击水印算法

为了提高水印系统抗剪切攻击的能力，设计了多变换域相融合的抗剪切水印算法.该算法中，用在宿主图像的每个分割区域中提取经DCT变换的最大系数值构成矩阵，再在此矩阵的SVD变换域中植入已加密的水印信息.实验结果表明，DCT与SVD相融合的水印算法不仅能够完全抵抗单一的剪切攻击，而且对常规图像处理和局部剪切联合攻击的抵抗性也较强，甚至在经过多个联合几何攻击后仍能提取清晰的水印.

An Watermarking Algorithm Against Cropping Attack Based on SVD and DCT

In order to improve the anti-attack capability of watermarking system against cropping attack, this paper presents an anti-cropping watermarking algorithm based on multi-transform domain. The DCT transform is carried out on each segmentation region of the host image and the maximum coefficients of each segmentation region are extracted to form a new matrix. The encrypted watermark information is then embedded into the singular value transformation domain of this matrix. Experiments show that the algorithm can not only fully resist the single cropping attack, it also has strong resistance to the joint attack of conventional image processing and local cropping. Even after multiple joint geometric attacks, it can still extract clear watermarks.