一种基于图象内容的小波域鲁棒水印技术

为了提高水印的鲁棒性及抗攻击能力，提出了一种基于图象内容的小波变换域水印技术，该技术是将水印内容的选取与原始图象的内容相联系，并在水印嵌入之前，先对水印进行伪随机排列，分块，扩展等预处理，以增强鲁棒性，其与传统的水印方法不同的是，在水印嵌入过程中选将分块后的水印嵌入，然后将整个水印嵌入，这样水印不仅嵌入到图象小波分解系数的低频分量中，也嵌入到高频分量中，而提取过程中，也同样提取分块后的水印和整个水印，并将基于图象内容的水印与事先给定水印在相同条件下进行了比较实验，实验结果表明，这种水印技术的鲁棒性明显好于传统水印技术，同时还证明了水印嵌入的容量不仅与视觉系统的刚刚可分辨门限有关，而且与水印信号本身的一些特性有关系。

A Digital Watermarking Technique with High Robustness Based on Content of Original Image in Wavelet Domain

In this paper a new digital watermarking technique is proposed based on discrete wavelet transform. In order to enhance the robustness of watermark, watermark was based on the content of the original image. Pesudorandom permutation, division and spectrum spread techniques were used to improve the robustness of watermark. Different from the traditional techniques, in our method, watermarks were embedded for two times, the holistic watermark was embedded first and then was divided watermark, and watermark here was embedded both into the low-frequency components of the wavelet transform of the image but also to the high-frequency components. The extraction process extracted both the holistic watermark and the divided watermark in turn. The watermark based on the content of the original image and the watermarks that given beforehand were compared in the same condition and the experimental results showed that this kind of watermark has a more robust than the techniques used the watermarks given beforehand. The experimental results also showed that the capacity of embedded watermark was related not only to the just noticeable difference of the human visual system but also to the characteristics of the watermark itself.