非线性限幅傅里叶计算全息的数字水印方法

Fourier Computer-Generated Hologram Digital Watermarking with Nonlinear Amplitude Limiting

基于信息光学理论提出了一种非线性限幅傅里叶计算全息的信息隐藏方法,使数字水印具有更好的稳健性。在传统傅里叶变换全息基础上提取计算全息图的振幅和相位,将相位信息作为输入函数,振幅信息转换成偏置函数,经过非线性限幅处理后得到二元傅里叶计算全息图。由于二元全息图比普通全息图具有更强的抗噪性能,从而大大提高了数字水印的稳健性。为了提高水印的抗压缩能力,通过离散余弦变换在频域嵌入宿主图像中。理论分析和仿真实验表明,该技术对有损压缩、剪切和滤波等多种图像处理操作均具有很高的稳健性,比传统傅里叶计算全息水印的稳健性有很大提高。

A new approach of Fourier computer-generated hologram （CGH） digital watermarking with nonlinear amplitude limiting is proposed, which realizes better robustness. The amplitude and phase are extracted on the basis of traditional Fourier transform holography. Binary Fourier hologram is formed by nonlinear amplitude limiting algorithm when the phase information as input function and the amplitude information transferred into a bias function, because the binary hologram has stronger anti-interference property than the normal hologram, and the digital watermarking of much better robustness can be obtained. To improve the watermark＇s resistance to compression, hologram is embedded in the frequency domain through discrete cosine transform. Theoretical analysis and numerical experiments show that the algorithm has more robustness to image lossy compression, cropping and filter, compared with the algorithm based on traditional Fourier CGH watermarking.