Optical double phase encryption and spreading technique applied to color image

In this work, we propose an encryption method based on optical double phase encoding and spreading techniques applied to color image. We implement two techniques to reinforce optical encryption, using single-channel double random-phase encoding technique. The color image to be encrypted is first separated into three color channels: red (R), green (G), and blue (B). The decomposed three RGB channels are multiplexed into a single image using spreading technique based on two dimensional Hadamard code. Two random-phase masks act as key parameters for the double optical encryption. The primary color images can be recovered exactly by applying correct keys followed by dispreading operation. We give analytical study of the proposed method. Numerical simulations demonstrate that the proposed scheme has considerably high security level and certain robustness against data loss. We have demonstrate a simple, secure and compact method to encrypt and decrypt a color image.