An optical encryption method based on double-threshold correspondence imaging

An optical cryptosystem called double-threshold correspondence imaging (DTCI) encryption method is proposed. In DTCI encryption, two thresholds are used to select the larger and smaller bucket detector values, and the object image can be recovered only by averaging the speckle patterns corresponding to these selected bucket detector values. Compared with the traditional computational ghost imaging encryption, the ciphertext of DTCI encryption is a group of serial numbers rather than all bucket detector values, which not only reduces the volume of ciphertext but also enhances the security. Furthermore, the average operation replaces the second-order correlation operation in the decryption process, simplifying the decryption process and reducing the time cost. And the feasibility and high security of this method are verified by computer simulations.