Optical image encryption based on multistage fractional Fourier transforms and pixel scrambling technique

A novel encryption for optical image based on multistage fractional Fourier transforms (FRTs) and pixel scrambling technique is presented in this paper. The principle of pixel scrambling is described and an optical approach to realize the pixel scrambling and decoding is also proposed. Numerical simulation results are given to verify the algorithm, and relative error (RE) between the decoded images and the original image versus the deviation of fractional orders is discussed. Comparing with single FRT encryption, the security using this method for optical image encryption is greatly improved due to the introduction of the pixel scrambling technique.