Photon counting imaging and phase mask multiplexing for multiple images authentication and digital hologram security

We propose an image encryption system based on phase mask multiplexing and photon counting imaging (PCI) technique for multiple image authentications and digital hologram security. Multiple images to be authenticated are converted into phase-only images using a phase-retrieval algorithm in fractional Fourier transform domain. The multiple phase-only images are multiplexed into a single phase-only mask and it is further encrypted into a complex-valued function. The photon-limited image is generated by applying the PCI technique to a complex-valued function. For decryption, the photon-limited decrypted images are obtained after applying the appropriate keys. The photon-limited decrypted image contains sufficient information for verification because this image has sparse representation. To verify the photon-limited decrypted image, the optical correlation filters can be used. The proposed system has also been used for hologram security. For hologram security, the system provides multiple layers of security by hiding multiple encrypted images. The computer simulation results have been presented. The authentication scheme has been tested for securing three-dimensional information through experimentally recorded Fresnel digital hologram. (C) 2015 Optical Society of America