图像拟仿射变换的DWT水印算法

摘要

It presented an digital watermarking algorithm based on DWT and quasi affine transformation. The algorithm uses quasi affine transformation to encrypt the watermark image in a limited integer field. Because quasi affine transformation has a good effect of the charateristics of scrambling and a longer period of scrambling. It is more secure than the common transformation,like Arnold and other geometric transformations.It extracts a number of blocks from the original image using chaotic sequence,and forms a new sub-image using those blocks,then makes the sub-image go to three wavelet transformations.The encrypted watermarking image is embedded into the sub-image, then the blocks of the sub-image are put into the original position in the original image. Experimental results show that this algorithm is robust and stable to common digital image processing operations.%提出一种图像拟仿射变换的 DWT 水印算法.该算法对水印图像的预处理采用有限整数域上的拟仿射变换,拟仿射变换有较好的置乱效果及较大的置乱周期,从图像信息加密的安全性角度来看,它优于 Arnold 等常见的几何置乱变换,利用混沌序列提取原始图像的若干块组成子图像,并对子图像进行三次小波变换,将加密图像嵌入到子图像中,并将子图像还原到原始图像的相应位置.实现了水印的透明性和鲁棒性.仿真实验结果表明,算法对常见的图像攻击具有较强的鲁棒性和稳健性.