Real-value Encryption for Optical Security System Based on Holography

A real-value encryption and decryption method is proposed for the optical image security system based on holography.A full-phase image to be encrypted stands side by side a black image in the same size.They together with a random phase mask are Fourier transformed and real part of the result is used as an encrypted image.The addition of encrypted image and the Fourier transformed of the random phase is inverse-Fourier transformed.The intensity values of inverse-Fourier transformed image is adjusted.It gives the exact original image.