基于NSCT和DWT的鲁棒数字水印算法

Robust Digital Watermark Algorithm Based on NSCT and DWT

针对现有水印算法难以有效对抗几何攻击的问题,提出一种基于非采样Contourlet变换(NSCT)的水印新算法。利用NSCT得到显著方向子带,对该子带系数进行二值化,获得图像边缘方向信息点集。在水印检测时,利用边缘方向的特征点集,可使受到几何攻击的水印化图像恢复到原来的大小和位置,即恢复已丢失的同步信息。实验结果表明,该方法对几何攻击具有很好的鲁棒性。

Aiming at the geometric attack problem of the digital watermark, a novel algorithm is proposed based on the NonsubSampled Contourlet Transform（NSCT）. Feature points are extracted by utilizing the characteristic of image from the greatly directional bandpass coefficients of the NSCT processed by binary. When watermark is detected, the feature points matching measure for the geometric manipulation is computed. The method can transform the image back to its original size/orientation, i.e, recover the lost synchronism. Experimental results show that it is robust to geometric attacks and other most common image processing manipulations.