基于扩频技术的图像盲水印算法

A Blind Image Watermarking AlgorithmBased on Spread Spectrum

基于小波变换的数字水印技术是当前的一个研究热点。本文把扩频通信的理论和方法引入到小波域数字水印系统中,提高了数字水印的隐蔽性和稳健性。水印信号经过伪随机序列调制扩频后,结合人眼视觉系统的纹理掩蔽特性和刚刚可分辨门限嵌入到载体图像的小波变换域。水印信息的检测不需要原始载体图像。该水印算法嵌入水印后难以察觉,对裁剪、噪声干扰、JPEG有损压缩和低通滤波有较强的鲁棒性。

The watermarking technology base on wavelet transform is the most active topic in digital watermarking. In this paper, theory and method in Spread Spectrum Communication have been applied to the embedding and detection of a watermarking in the wavelet-domain and the invisibility and robustness of the watermarking are increased. Using a pseudo-random noise spread sequence to spread spectrum of the watermarking and modulate the watermarking, we insert the watermarking into the DWT domain of the cover image by exploiting and depending on the feature of visual masking and just noticeable difference of human vision system. By used the same pseudo-random sequence and determined its correlation with the transformed detail bands of the watermarked image, blind recovery of the embedded message is achieved. The experiment results demonstrate that the watermarking is perceptually invisible and the proposed algorithm is robust enough to some image degradation process such as cropping, noise, JPEG compression, Low-pass Filtering, and other attacks.