Security optical systems based on a joint transform correlator with significant output images

Abstract

Abstract. An improved optical security system based on correlation between two phase-only computer generated masks is proposed. The two phase masks are placed together at the input plane of a joint transform correlator. A priori known output image is obtained in the system output only if one mask is the right key for the other mask. In addition to a simple verification, our security system is capable of identifying the type of an input mask according to the corresponding output image that it generates. The two phase masks are designed using an iterative optimization algorithm with constraints in the input and output domains. Computer simulations are presented with the resultant images formed by the two phase-only elements. © 2001 Society of Photo-Optical Instrumentation Engineers.

Steganography and Encryption Systems Based on Spatial Correlators with Meaningful Output Images

“…In this section we review our security scheme implemented in the JTC [2]. The main advantage of this scheme over the 4f correlator described in the previ- ous section is the less restrictive alignment requirements.…”

“…(1) Optical systems have an inherent capability for parallel processing; that is, rapid transmission of information. (2) Information can be hidden in any of several dimensions, such as phase or spatial frequency; that is, optical systems have excellent capability for encoding information.…”

“…The next generation of these security systems should offer a higher level of security and more sophisticated services than the simple verification offered by the existing systems. In this chapter, we survey three optical security systems [1][2][3] that are based on existing spatial correlators but have some additional benefits over those of the first generation. The common feature of all three systems is meaningful images on the output plane of the correlators.…”

“…In this configuration, the key mask is displayed on the correlator's input plane, whereas the lock mask is displayed on the correlator's frequency plane. The joint transform correlator (JTC)-based security system [2] described in Section 4.3 overcomes inherent difficulties that exist in the 4f correlator. In Section 4.4, we survey a new development in our general paradigm called Concealogram.…”

A cascaded iterative Fourier transform algorithm for optical security applications

“…To reconstruct the original information, the phase functions exp{jp(x, y)} and exp{jb(u, v)} must match and be located in the input and the Fourier plane respectively. Abookasis et al [11] implemented this scheme with a joint transform correlator for optical verification.…”