Double images hiding by using joint transform correlator architecture adopting two-step phase-shifting digital holography

Based on the joint Fresnel transform correlator, a new system for double images hiding is presented. By this security system, the dual secret images are encrypted and recorded as intensity patterns employing phase-shifting interference technology. To improve the system security, a dual images hiding method is used. By digital means, the deduced encryption complex distribution is divided into two subparts. For each image, only one subpart is reserved and modulated by a phase factor. Then these modified results are combined together and embedded into the host image. With all correct keys, by inverse Fresnel transform, the secret images can be extracted. By the phase modulation, the cross talk caused by images superposition can be reduced for their spatial parallel separation. Theoretical analyses have shown the system's feasibility. Computer simulations are performed to show the encryption capacity of the proposed system. Numerical results are presented to verify the validity and the efficiency of the proposed method.