基于小波和傅立叶变换组合的数字图像水印算法

数字水印技术是实现版权保护的有效办法之一.为实现水印图像的嵌入,提出了一种基于二维离散小波与傅立叶变换组合的灰度图像数字水印算法.首先对原始图像进行离散小波变换,选择低频子带图像LL作为水印的添加区,再将LL区进行分块,并对每一个小块作离散傅立叶变换;对嵌入的水印图像做相应的分块置乱处理,而后根据人眼视觉系统的特点结合边缘分析将水印信息以不同的强度嵌入载体图像中,最后进行傅立叶和小波逆变换生成密图.实验结果表明,算法具有较好的鲁棒性和视觉效果.

A method of digital image watermarking based on wavelet and Fourier transform

The technique of digital watermark is one of the valid methods for copyright protection. In this paper, we propose a digital watermarking algorithm with gray image based on 2-dimensions discrete wavelet and Fourier transform. In order to embed the image's watermark, we transformed the image into discrete wavelet domain, and split the lower frequency image of horizontal and vertical direction into subblocks, then we transformed every block into discrete Fourier domain. Based on the feature of human visual system and edge analyses, the watermarking components with different strength, which was split corresponding to LL's and disorderly dealt with, were embedded into cover image. Finally, the secret image was obtained by reverse transform of wavelet and Fourier. The experimental results show that it has excellent robustness and visual effect.