Optical color image encryption without information disclosure using phase-truncated Fresnel transform and a random amplitude mask

Many phase-truncation-based cryptosystems encounter an information disclosure problem. In this paper, a novel color image encryption using a phase-truncated Fresnel transform and random amplitude mask (RAM) without the risk of information disclosure is proposed. An image is first separated into three channels (red, green, and blue) and using an additional RAM channel the risk of information disclosure encountered in previous encryption methods is eliminated. Moreover unlike previous methods where each channel is encrypted independently, the four channels employed in the proposed method are encrypted using a cascading technique. Robustness of the proposed scheme against attacks is analyzed. Numerical simulations are presented to demonstrate the feasibility and effectiveness of the proposed system.