提出了一种基于双随机相位的图像实值编码方法,该方法可应用于光学图像加密.要编码的纯相位图像分别在空间域和频域加入随机相位掩膜,其中在频域将编码范围扩大4倍,经过光学系统的变换,将生成的图像取实部作为编码图像.实值编码的图像利用与编码过程类似的方法进行解码,可以准确地重建原图像.该编译码方法简单,编码图像是一个近似随机噪声的实值图像,便于数字图像的传输与输出.

The double random phase real-value encryption and decryption method is proposed for the optical image security system.A phase-only image to be encrypted together with a random phase mask in space plane is Fourier transformed .Then it attached anther random phase mask in Fourier plane is enlarged and reverse-Fourier transformed .Real part of the result is used as an encrypted image. The decryption of the real-value encrypted image can be carried out in the same means with encryption. That gives the exact original image. The method of encryption and decryption is simply performed and encrypted image is real-valued,so it is convenient for output.