小波域中基于分形压缩的数字图像盲水印算法

New blind digital image watermark algorithm based on fractal compression in wavelet transformation domain

在小波域中利用分形压缩理论提出了一种图像数字水印算法。对图像进行小波变换后,首先将整个小波树分成3个方向的小波子树,然后按照方向性小波树进行分形编码,并通过对分形编码仿射变换的不同分类实现数字水印的嵌入,而且为了增加水印破解的难度,水印信息经过了行、列两个方向的混沌置乱。另外,水印检测时也不需要原始图像。实验结果表明,该算法不仅克服了传统分形算法运算量大的缺点,而且对JPEG压缩、高斯噪声、剪切等攻击也有较强的抵抗能力,水印的鲁棒性和稳健性较好。

A new blind watermark algorithm in wavelet domain based on fi-actal compression is presented. The fi＇actal encoding is performed on the coefficients at various orientations wavelet sub-trees for a certain wavelet block having self-similarity, and the watermark sequence are embedded in host image by classifying affine transformations into different groups. In addition, in order to enhance the randomicity of watermark sequence, the chaotic permutation is performed on the row and column of it. The most important thing is that the original image is unnecessary in the process of detecting watermark. We tested the algorithm performance in terms of different Stirmark attacks, such as JPEG compression, middle-value filtering, noise interference. The experimental results show that the algorithm has great improvement on the watermark robustness and security.