小波域内的盲水印提取

在对水印嵌入位的假设检验基础上，提出了一种盲水印的逐位提取模型，并在小波域得到了实现.为平衡水印的不可见性和鲁棒性，根据图像小波域的特征，并利用上下文建模的方法为每个高频小波系数确定不同的水印幅度，从而使水印的嵌入强度依图像的特征而变化.由于水印提取的结果在很大程度上依赖于图像小波系数的统计分布模型，因此小波域中的系数建模采用了广义高斯分布，并使用极大似然法估计参量.实验表明，该方法具有良好的鲁棒性.

Blind Image Watermarking Extraction In DWT Domain

Based on the hypothesis testing of the watermark bits,a model of the blind watermark extraction is presented and implemented in the wavelet domain,which can extract the watermark bit by bit. To balance the imperceptibility and robustness of the watermark,the wavelet features of the image and the context modeling method are utilized to determine the variable watermark amplitude for every high frequency wavelet coefficient. So the embedding density of the watermark is adaptive to the image features. The watermark extraction results are dramatically based on the distribution model of the image's wavelet coefficients,thereby the wavelet coefficients are modeled as a general gauss distribution,and the parameters are estimated by the maximum likelihood method. A series of experimental results show that the method is robust.