Single-channel optical encryption of color image using chessboard grating and diffraction imaging scheme

A single-channel encryption method for color images is proposed using chessboard grating and a phase-retrieval algorithm in the Fresnel domain. The pixel sampling operation is introduced to convert the color image to be encrypted into a Bayer image. Thereafter, with a single channel, the Bayer image is encoded by the chessboard grating before being sent into a diffractive-imaging-based encryption scheme. The cryptosystem is simple owing to only one single intensity pattern being required during encryption. In the decryption procedure, the phase-retrieval algorithm and the chessboard grating are combined to extract the plaintext from the intensity pattern. This proposal not only can successfully encrypt a color image into a single diffractive intensity pattern but also can recover the primary color image with high quality from the one single diffraction pattern with a compact optical setup. Numerical simulations are carried out to prove the feasibility and validity of the proposal.