An optical multiple-image authentication based on transport of intensity equation

Abstract

An optical multiple-image authentication approach based on transport of intensity equation technique has been proposed. Initially, a phase-encoded plaintext is synthesized with significant blocks chosen from the multiple plain images by evaluating their spatial frequency coefficients, which is bonded with a random intensity mask generated with logistic map to constitute the complex amplitude. Then, the complex amplitude is encrypted to a real-valued ciphertext with noise-like distribution by using Fresnel diffraction. In the process of authentication, the phase information is firstly reconstructed by solving transport of intensity equation. The existence of a plain image can be identified by calculating the nonlinear correlation between it and its partial data only containing the extracted significant blocks from the phase information by aid of the corresponding binary mask. To our best knowledge, it is the first time to apply the transport of intensity equation technique to implement the optical multiple-image authentication. A set of numerical simulations are carried out to demonstrate the feasibility of the proposed approach.