基于位扩展的小波域彩色数字水印算法

A digital watermarking technique for color image based on bit expand and DWT

提出一种应用于彩色图像版权保护的水印方法。为保证水印的安全性,在嵌入之前先对水印图像作置乱处理,再将水印图像位扩展为原始图像的两倍大小;然后根据HVS和小波变换的多分辨率分解特性,将位扩展水印和原始彩色图像蓝色分量对应方向上的子带系数进行组合。通过实验验证,该算法在对嵌入水印后的图像进行JPEG有损压缩、剪切、不规则色块污染、添加各种噪声处理后,提取出的水印表现了较好的鲁棒性,且主观视觉失真较小。

A watermark technique applying to copyright protection of color images was proposed. To ensure the security of wartermark, the wartermark image was scrambled before embedding and then expanded to the twifold size of the original image. The corresponding subband data of the watermark and the blue weight for original image were combined according to the characteristic of the multiresolution decomposition of the wavelet transform. The method has been tested with attacks such as JPEG lossy compression, cropping, polluting and noise adding, obtaining results of good robustness and low visual distortion.