Image encryption and decryption using computer generated holography

Abstract

Holography is an optical technique to generate the interference pattern of the light field created from the interference of two coherent light sources, one being scattered from an object and another reference light being sent directly into the holographic plate. This interference pattern is then used in a 3D holographic display to view the holographic representation of the object. This is done by passing the same reference light through the interference pattern fringe in the 3D display. Computer Generated Holography (CGH) is a simulation technique to generate the same interference pattern without the object being present. Usually this is done by taking an image or a 3D representation of the object and using numerical techniques to simulate the interference pattern of the light field. CGH has many applications and one of them is image encryption and decryption. This paper describes how to generate a CGH of an image, how to overcome the general problems, namely the image overlapping problem during the reconstruction of the image from the interference pattern and how to encrypt an image and then decrypt it using the properties and principles of CGH.