一种基于分形编码的小波域自适应水印

提出了一种基于分形编码的小波域水印算法．该方法对于图像树中各个图像R块，首先在同方向低一级分辨率子带中寻找最佳分形匹配D块，然后利用小波系数的树状结构关糸，将这些D块拓展成相似树集合，最后更改图像树上某个位于中频子带的图像R块的编码方案，即交换最优和次优匹配相似树上与其对应的D块，从而实现数字水印的嵌入．水印检测不需要原始图像．实验结果表明：使用该方法的水印有较好的不可感知性和鲁棒性，同时可保证较低的正向错误率．

Adaptive Watermarking Based on Fractal Image Coding in Wavelet Domain

An adaptive watermarking based on fractal image coding in wavelet domain is described.The optimum fractally-matched domain block is searched in the subimage of the same orientation but lower resolution than that of the range block.According to tree structure relation of the wavelet coefficients,the domain blocks can extend through different resolutions along the same orientation to form a set of domain trees.Each watermark bit is embedded by modifying code of a certain range block from range tree,i.e.substituting the corresponding domain block of the first-matched domain tree for that of the second-matched dormain tree.The embedded sequence can be extracted without restoring to the original unmarked image.The experimental results show that the watermark is invisible and robust and extraction keeps the false positive rate significant small.