Optical encryption in a JTC encrypting architecture without the use of an external reference wave

•we propose a new encryption-decryption protocol by use of a JTC architecture.•The implementation of the protocol is completely free from a reference wave.•The proposal retrieves images with better quality compared with the former method.•Images for hidden the original image is reduced to a minimum number of 4.•The Dirac function employed is extremely simple for generation by optical method.

In practical optodigital encrypting architectures, the use of a reference wave is always necessary. In this paper, we present a protocol for image encryption and decryption by the use of a JTC architecture without the need of an external reference wave. We describe the practical implementation of this architecture, along with computer simulation results that support the proposal. We also find that image retrieved by our approach owns a better quality compared with that by the conventional method. Besides, some other advantages of the proposed protocol are discussed.