A Two-Step Phase-Shifting Compressive Optical Image Encryption and Hiding System Based on a Mach–Zehnder Interferometer (MZI)
N. Xu, Z-Y. Zhang, J. Li and Z-H. Huang
A two-step phase-shifting compressive optical image encryption and hiding system based on a Mach-Zehnder interferometer (MZI) and verified with a He-Ne laser beam is proposed. The object image was first encrypted using two random-phase masks in the two-step phase-shifting optical image encryption and hiding part of the system. After the encrypted image was hidden in the host image, two encrypted holograms were generated via the interference of the reference and object lights. To reduce the number of measurements, the two interference holograms were then compressed and sampled into one-dimensional (1-D) data in the single-pixel camera part of the system. Lastly, once the two holograms were reconstructed using the two-step iterative shrinkage/thresholding (TwIST) algorithm, they were imported into a two-step phase-shifting optical image encryption and hiding reconstruction program, where the original object image before encryption was restored. The simulation results suggested that the system demonstrated both good security and robustness.
Keywords: He-Ne laser, Mach-Zehnder interferometer (MZI), two-step phase shifting, optical image encryption, optical image hiding, compressed sensing, information security