基于级联分数傅里叶变换系统的数字水印技术

提出一种基于分数傅里叶变换和随机相位编码的光学加密数字水印技术,可成为一种信息隐藏及保护的有效方案.该数字水印技术对于噪音叠加和常见的图像处理操作具有较强的稳健性.该技术根据光学级联分数傅里叶变换系统,利用两个随机相位分布函数对水印信息编码并经过迭代分数傅里叶变换嵌入到变换域的载体图像中.在水印检测和提取过程中,两个相位分布函数作为密钥.随机相位编码技术的引入,进一步提高了数字水印系统的密钥空间.增强了系统的安全性.该数字水印技术基于光学分数傅里叶变换原理,可以利用光学变换系统方便地实现.

Digital Watermarking Technique Based on Cascaded Fractional Fourier Trans form System

A novel digital watermarking method by optical cascaded fractional Fourier transform and random phase encoding is proposed. This method can be served as an effective way of information hiding and protection. Experimental results show that this watermarking method has strong robustness against noise, shearing, rotation, resizing, and medium filtering. This watermarking method is based on optical cascaded fractional Fourier transform system. The watermark information is iterative fractional Fourier transformed and embedded into host image. And two phase distributions can be obtained as keys to protect the watermark information. With the introduction of double phase encoding, the key space of this watermark system is greatly enlarged. As a result the security of this watermark system is enhanced. This watermark technique can be implemented both optically and digitally.