Optical encryption by combining image scrambling techniques in fractional Fourier domains

In this paper, we propose a novel scheme for optical information hiding (encryption) of two-dimensional images by combining image scrambling techniques in fractional Fourier domains. The image is initially randomly shifted using the jigsaw transform algorithm, and then a pixel scrambling technique based on the Arnold transform (ART) is applied. The scrambled image is then encrypted in a randomly chosen fractional Fourier domain. These processes can then be iteratively repeated. The parameters of the architecture, including the jigsaw permutation indices, Arnold frequencies, and fractional Fourier orders, form a very large key space enhancing the security level of the proposed encryption system. Optical implementations are discussed as numerical implementation algorithms. Numerical simulation results are presented to demonstrate the system's flexibility and robustness.