Multi-image encryption based on three-step phase-shifting digital holography

As a cutting-edge imaging technology that combines optical holography principles with digital signal processing, digital holography holds significant potential for applications in optical image encryption. However, current optical image encryption methods based on digital holography are predominantly designed for single images. With the rapid development of big data, the Internet, and modern communication technologies, single-image encryption methods have increasingly struggled to meet the growing demands for image data privacy protection. Furthermore, the robustness of most existing optical image encryption methods has not been sufficiently validated through communication experiments. Therefore, this paper proposes a multi-image encryption scheme based on three-step phase-shifting digital holography. In this proposed scheme, a chaotic system is used to generate random phase mask keys during the encryption and decryption processes. This not only enhances the security of the encryption system but also simplifies the management and transmission of secret keys. By employing wavelet decomposition and reconstruction, this proposed scheme can simultaneously encrypt four grayscale images, thereby improving the efficiency of image encryption. Simulation results indicate that the proposed scheme offers high security, effectively resisting brute force attack. Additionally, orthogonal frequency division multiplexing (OFDM) communication experiments demonstrate that the proposed scheme is also highly robust.