Generalized Arnold map-based optical multiple color-image encoding in gyrator transform domain

Abstract

A novel optical multiple color-image security system based on generalized Arnold map in gyrator transform domain is investigated. In this cryptosystem, a color image is decomposed into R, G, and B channels. Each channel is independently permutated with generalized Arnold map and then gyrator transformed. The gyrator spectrum of each channel is multiplied together to generate a single-channel encrypted image. Similarly, multiple images are processed separately to produce their respective single-channel encrypted images. After that all the single-channel encrypted images are combined to construct a single encrypted image as input information and multiplied with a random phase mask, and then phase- and amplitude-truncated to get the first encrypted image and first asymmetric key, respectively. Finally, the first encrypted image is gyrator transformed and then phase- and amplitude-truncated to obtain the final encrypted image and second asymmetric key, respectively. The individual decryption key, random phase key, asymmetric keys, transformation angles, control parameters, and initial conditions significantly enhance the security of the system and thus ensure the resistance against existing attacks. In addition, this method avoids crosstalk noise and consequently increases the multiplexing capacity. The proposed system can be implemented by using optoelectronic architecture. Numerical simulation results are presented to test the validity and security of the proposal.