Image encryption based on Walsh Hadamard and fractional fourier transform using Radial Hilbert Mask

Abstract

In this letter an approach for double image encryption practicing Double Random Phase Encoding (DRPE) technique that is based on Walsh Hadamard transform (WHT) and fractional Fourier transform (FRT) is proposed. The encryption scheme incorporates Radial Hilbert Mask (RHM), Random Phase Mask (RPM) and fractional order as the keys. Using the 4-f system of DRPE twice in both the WHT and FRT domain, each image is encoded independently with the presented scheme. Matlab simulation tests demonstrate the increase in security level of the classical DRPE technique by the designed optical cryptosystem, and it has a superior insusceptibility to noise also. The efficiency and sensitivity of the presented scheme is tested by calculating MSE and PSNR. The histogram shows that the energy is conserved by using Walsh Hadamard transform and shows that the encrypted image is much easy to transfer due to the compression property of WHT.