Optical hiding with visual cryptography

摘要: Classical optical hiding methods are symmetric, being apt to realize but not secure. The security is improved in existing non-symmetric hiding techniques, yet all of them fails in convenient extractions, still not optically realized so far. Here, we propose an asymmetric optical hiding method based on visual cryptography, achieving the high security and the easy extraction at the same time. In the hiding process, we convert the secret information into a set of fabricated phase-keys, which are completely independent of each other, intensity-detected-proof, and image-covered, this complex hiding procedure leading to the high security. Correspondingly, during the extraction process, the covered phase-keys are illuminated with laser beams and then incoherent superposed to extract the hidden information directly by human visual system, without complicated optical implementations and any additional computation, resulting in the convenience of extracting. Optical experiments verify that both the high security and the easy extraction are obtainable in the visual-cryptography-based optical hiding.