Abstract
This paper presents two optical double image encryption systems using the Fresnel Transform (FrT) and chaotic maps (CM) such as the baker map (BM) and the Arnold's Cat map (ACM). The two proposed optical double CM-based FrT image encryption systems are BM-FrT based optical double image encryption and ACM-FrT based optical double image encryption. In the two proposed optical double CM-based FrT image encryption systems, the image is firstly scrambled using the BM or the ACM then, modulated with the first random phase mask, and optically transformed using the FrT. The FrT scrambled image is then again scrambled using the BM or the ACM then, modulated with the second random phase mask and optically transformed with the FrT to get the encrypted image. The usage of a chaotic map as a pre-processing scrambling stage along with the FrT gives the two proposed optical encryption systems the advantages of both the noise immunity from the chaotic map and the security encryption from the FrT. Also, the optical FrT geometric parameters are utilized as additional extra keys that improve the security of the two proposed optical double CM-based FrT image encryption systems. The two proposed optical double CM-based FrT image encryption systems are extensively tested and compared with other encryption systems. The outcomes demonstrated that the proposed BM-FrT based optical double image encryption and ACM-FrT based optical double image encryption enhance the entropy over BM and ACM by a range from 2.02 to 128.23% and 2.06 to 128.16%. The results show that the two proposed optical double CM-based FrT image encryption systems are time-efficient and provide a high level of information security without affecting its noise immunity.