Visual cryptography based on ghost imaging and Hadamard transform

Visual cryptography is a potentially important technique for optical information security. However, the limitations of carrier materials and the high precision requirements of the reconstruction process limit the application scope of visual cryptography. Herein, we propose a novel visual cryptography technique based on ghost imaging. The spatial information on one visual key image is encoded into time-varying factors in ghost imaging and loaded onto Hadamard illumination patterns. The secret image can be recovered when the illumination patterns are projected onto another visual key image. This method utilizes light-intensity superposition to overlap visual key image pixels. Simulation and experimental results substantiate the feasibility and security of the proposed technique. This method incorporates the unique advantages of ghost imaging and visual cryptography and is not limited by carrier materials and precision. Hence, it has high scalability and broad application scenarios in ghost imaging broadcasting systems and information authentication, among others.