一种小波变换域的自适应视频水印算法

稳健性是数字水印算法的主要问题之一.根据视觉特点和信号特性实现水印分量的自适应嵌入是提高水印稳健性的有效途径.本文提出了一种基于小波变换域的自适应视频水印算法.水印根据2-D小波系数的特点嵌入在低频子带系数中,以获得较好的稳健性.为了在保证不可见性的前提下尽可能提高水印分量的强度,本文提出根据物体的运动和视频信号内容的纹理复杂度将低频子带中的系数进行分类,根据分类结果,自适应地调整嵌入水印的强度.实验结果表明:嵌入水印对多种攻击,如加性Gaussian噪声、高压缩比的MPEG-2压缩编码、时域抽样和丢帧、以及空域抽样等具有很好的稳健性.

An Adaptive Video Watermarking Algorithm in Wavelet Domain

Robustness is one of the major issues of digital watermarking algorithms.An effective method to improve the robustness of watermark is to embed the watermark adaptively based on the human visual system and signal characteristics.In this paper,an adaptive video watermarking algorithm in wavelet domain is proposed.According to the properties of the 2 D wavelet coefficients,the watermark is inserted into the coefficients of LL subband to achieve better robustness performance.In order to enhance the strength of the components of the watermark,we propose to classify the wavelet coeffcents based on the motion of the objects and the texture complexity of the contents in the video sequence.According to the result of classification,the strength of the watermark components is adjusted adaptively.Meanwhile,the transparency of watermark is guaranteed.The experiemental results show that the proposed watermarking algorithm is robust to video degradation and distortions,e.g.,those that result from additive Gaussian noise,MPEG 2 coding at high compression ratio,temporal downsampling and spatial downsampling.