A technique that increases the efficiency of a conventional joint-transform correlator is proposed. By modifying the joint-transform power spectrum of the input objects by using a spatial sampling method, the readout light as well as the physical area of the square-law detector can be fully utilized. As a result, the output correlation intensity can be substantially increased. Cases of using coherent and partially coherent readout light are discussed, and experimental results are presented.
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We present, to our knowledge, a novel method to achieve experimental encryption using double random phase encoding with full complex modulation and a single phase-only spatial light modulator. Our approach uses double phase encoding to generate phase-only holograms containing complex-valued input planes for a joint transform correlator (JTC) cryptosystem. This approach enables users to independently manipulate both the phase and amplitude of the cryptographic keys and objects, thereby significantly enhancing the versatility of the optical cryptosystem.
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Grupo de Óptica e Informática, Department of Physics, Universidad Popular del Cesar, Valledupar 200001, Cesar, Colombia.
A novel nonlinear encryption-decryption system based on a joint transform correlator (JTC) and the Gyrator transform (GT) for the simultaneous encryption and decryption of multiple images in grayscale is proposed. This security system features a high level of security for the single real-valued encrypted image and a high image quality for the multiple decrypted images. The multispectral or color images are considered as a special case, taking each color component as a grayscale image.
View Article and Find Full Text PDFDouble Image Encryption System Using a Nonlinear Joint Transform Correlator in the Fourier Domain.
Sensors (Basel)
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Grupo de Óptica e Informática, Department of Physics, Universidad Popular del Cesar, Valledupar 200001, Cesar, Colombia.
In this work, we present a new nonlinear joint transform correlator (JTC) architecture in the Fourier domain (FD) for the encryption and decryption of two simultaneous images. The main features of the proposed system are its increased level of security, the obtention of a single real-valued encrypted signal that contains the ciphered information of the two primary images and, additionally, a high image quality for the two final decrypted signals. The two images to be encrypted can be either related to each other, or independent signals.
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Sensors (Basel)
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Electronic Technology and Reliability Department, University Politehnica of Bucharest, 060042 Bucharest, Romania.
Optical correlators are efficient optical systems that have gained a wide range of applications both in image recognition and encryption, due to their special properties that benefit from the optoelectronic setup instead of an all-electronic one. This paper presents, to the best of our knowledge, the most extensive review of optical correlators to date. The main types are overviewed, together with their most frequent applications in the newest contributions, ranging from security uses in cryptosystems, to medical and space applications, femtosecond pulse detection and various other image recognition proposals.
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