Performance of double phase encoding encryption technique using binarized encrypted images

Abstract

We investigate the performance of an image encryption tech- nique that uses random-phase encoding in both the input plane and the Fourier plane, using partial information of the encrypted image. We first investigate the phase-only information of the encrypted data for decryp- tion. A binary version of the phase-only information is also considered for decryption. Binary images are well suited for optical display and practical implementation. Using partial information of the encrypted image, a re- constructed complex image is generated, which is used for decryption. Tests are performed for both gray-scale and binary images. We show that the phase information of the encrypted image is very important in the reconstruction of the decrypted image. Computer simulations show that for the images tested here, binarization of the encrypted image can re- cover the original image with low mean squared error. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)04302-5) noise. 3 The fault-tolerance properties of this technique were investigated in Ref. 4. In this paper, we evaluate the phase information of the encrypted image and investigate the ef- fect of its binarization on the recovered image. We give the reasons for the binarization of the encrypted image, and tackle the problems raised by it. It is shown that postpro- cessing of the decrypted image can improve the quality of the recovered images. We show, for the images tested here, that recovered images of very good quality can be obtained.