Three-dimensional image encryption based on structured light illumination and an iterative layer-oriented angular-spectrum algorithm

Abstract

In this paper, a three-dimensional (3D) image encryption method is proposed based on structured light illumination and an iterative layer-oriented angular-spectrum algorithm, where the original 3D plaintext image is encrypted into a phase-only hologram ciphertext (POHC). The structured light is generated by using a structured phase mask (SPM), and the optical parameters in the SPM all serve as the supplementary keys for increasing the types and quantities of security keys, expanding the key space and enhancing the level of security. Moreover, the introduction of structured light also enhances the invisibility of the ciphertext and concealment of the valid information, overcoming an inherent silhouette problem of the POHC calculated by a traditional layer-oriented angular-spectrum algorithm, and the iterative calculation also suppresses the speckle noise of the decrypted 3D image, improving the decryption quality. Numerical simulations are performed to demonstrate the feasibility of the proposed 3D image encryption method, and the simulation results show that the proposed method exhibits a high feasibility and security, as well as strong robustness.