一种基于小波变换和变换域系数值比较的数字水印算法

THE DIGITAL WATERMARKING BASED ON THE DWT AND COMPARING THE VALUE OF POST MEDIA

提出了一种基于小波变换和变换域系数值比较的盲检测数字水印算法。算法利用小波变换,将载体图像进行多层小波变换分解,找出合适的变换域系数,将该系数分解为数据对序列,使二值水印图像每个像素的值与该数据对序列中的每个数据对一一对应。用数据对内前后数据值的大小关系来表示0和1,若前者大于后者,则表示1;若后者大于前者,则表示0。然后调整数据对序列中每个数据对内数据的前后位置,使其和二值水印图像相应位置上的像素值匹配。这样就嵌入了水印。提取水印过程刚好和嵌入水印过程相反。实验证明,水印具有透明性,对高斯低通滤波、图像变亮、图像变暗、直方图均衡化、增加图像对比度、降低图像对比度、添加高斯噪声、添加椒盐噪声、添加乘积性噪声、JPEG压缩等图像处理和噪声干扰都具有很强的鲁棒性。该算法鲁棒性和透明性好,是一种可行的水印方案。

This paper proposed an algorithm of digital watermark based on wavelet domain and comparing the value of post media. Firstly, the image that will be embedded the watermark is resolved with the discrete wavelet transform, and choose the appropriate coefficient, divided it into the pair of value according the order of coordinate relation. Secondly, make the pair of value correspond to the value of the digital watermark image of binary. Thirdly, to make sure that the logical relationship of the pair value is same as the bit of digital watermark image, so the digital watermark is embedded. The way of extract the digital watermark is same as the way of embed the digital watermark, and the process is reverse. The principle of the algorithm is simple,the robustness and the concealment of the algorithm are very well. The algorithm is feasible.