基于关键点信息的鲁棒参考水印算法

Robust Reference Watermarking Algorithm Based on Key Points

鲁棒参考水印 (RRW)算法是基于小波多分辨分析的用于静态图像的数字水印算法 ,在分析了RRW算法在图像小波分解系数的平均值较小时的缺陷的基础上 ,根据人眼视觉原理 ,提出了利用水印的关键点信息来改进RRW算法的思想 .与常规RRW算法不同 ,算法使用关键点信息 ,在对小波系数进行特征量化时 ,对关键点取较小的Q值 ,对非关键点取较大的Q值 .在水印检测中 ,对关键点和非关键点赋予不同的权值 ,并深入分析了该方法的正向错误概率和负向错误概率的计算公式 .实验结果表明 ,改进算法不但其性能优于原算法 ,而且还在一定程度上缓解了水印的不可见性和健壮性之间的矛盾 .

Robust Reference Watermarking (RRW) is a digital watermarking algorithm of still images based on the concept of multiresolution wavelet fusion. The concept of Key points is applied to watermarking in order to improve the robustness of RRW. Normal RRW uses only a constant Q to quantize wavelet coefficient. In the quantization process of improved method, if the watermark point is key point, then use larger quantizing parameter Q to quantize wavelet coefficient, else use smaller Q. When detecting watermark, key points' weight value are 1, and others' are constant not smaller than 0 and not larger than 1. Analysis is provided to compute the probability of false positive and false negative results. Experimental results show the performance of our method is better than the original RRW method and demonstrate its potential for the robust watermarking of photographic imagery.