Review of Optical Cryptosystem for Gray Image and Color Image

Optical information security is one of the most important research directions in information science and technology, especially in the copyright protection, confidential information transmission/storage and military remote sensing. Since double random phase encoding technology (DRPE) was proposed, optical image encryption technology has become the main topic of optical information security and it has been developed and studied deeply. Much significant research and investigation on optical image encryption have been presented based on DRPE or further optical operation, such as digital holography, and Fresnel transform, gyrator transform. In this paper, the optical encryption system for gray image and color image is reviewed.