Joint Transform Correlator Research Articles

Optical double-image cryptosystem based on a joint transform correlator in a linear canonical domain

In this work, we present a new optical double-image encryption method based on a joint transform correlator (JTC) and the linear canonical domain for the simultaneous authentication of two images. This new extension of the encryption system overcame the vulnerability of the method based on the JTC and the conventional 4f-optical processor in the Fourier domain. Although the simultaneous authentication process is satisfied in the Fourier domain, the data content is partially disclosed in false validation. Therefore, we introduce a quadratic phase encryption system of the linear canonical transform (LCT) domain in this method. The linear canonical transform domain adds more degrees of freedom to the security method due to the six LCT orders. In addition, the double-image encryption scheme became secure against intruder attacks, and it was difficult to recognize confidential information during the negative validation process. A cryptanalysis is performed in terms of a chosen-plaintext attack (CPA) and chosen-ciphertext attack (CCA). Numerical simulations demonstrate the feasibility, security, and effectiveness of the proposed system.

Experimental optical encryption with full complex modulation

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. We validate the capabilities of our proposed scheme by generating optimized random phase masks and using them to experimentally encrypt various grayscale and binary objects. The experimental complex modulation obtained with the system detailed in this work, in conjunction with optimized random phase masks, results in an enhancement in the quality of the decrypted objects during reconstruction. Both numerical simulations and experimental findings corroborate the effectiveness of our proposal.

Nonlinear Encryption for Multiple Images Based on a Joint Transform Correlator and the Gyrator Transform.

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. All multiple grayscale images (original images) to encrypt are encoded in phase and placed in the input plane of the JTC at the same time without overlapping. We introduce two random-phase masks (RPMs) keys for each image to encrypt at the input plane of the JTC-based encryption system. The total number of the RPM keys is given by the double of the total number of the grayscale images to be encrypted. The use of several RPMs as keys improves the security of the encrypted image. The joint Gyrator power distribution (JGPD) is the intensity of the GT of the input plane of the JTC. We obtain only a single real-valued encrypted image with a high level of security for all the multiple grayscale images to encrypt by introducing two new suitable nonlinear modifications on the JGPD. The security keys are given by the RPMs and the rotation angle of the GT. The decryption system is implemented by two successive GTs applied to the encrypted image and the security keys given by the RPMs and considering the rotation angle of the GT. We can simultaneously retrieve the various information of the original images at the output plane of the decryption system when all the security keys are correct. Another result due to the appropriate definition of the two nonlinear operations applied on the JGPD is the retrieval of the multiple decrypted images with a high image quality. The numerical simulations are computed with the purpose of demonstrating the validity and performance of the novel encryption-decryption system.

Double Image Encryption System Using a Nonlinear Joint Transform Correlator in the Fourier Domain.

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. The encryption system is based on the double random phase encoding (DRPE), which is implemented by using a nonlinear JTC in the FD. The input plane of the JTC has four non-overlapping data distributions placed side-by-side with no blank spaces between them. The four data distributions are phase-only functions defined by the two images to encrypt and four random phase masks (RPMs). The joint power spectrum (JPS) is produced by the intensity of the Fourier transform (FT) of the input plane of the JTC. One of the main novelties of the proposal consists of the determination of the appropriate two nonlinear operations that modify the JPS distribution with a twofold purpose: to obtain a single real-valued encrypted image with a high level of security and to improve the quality of the decrypted images. The security keys of the encryption system are represented by the four RPMs, which are all necessary for a satisfactory decryption. The decryption system is implemented using a 4f-processor where the encrypted image and the security keys given by the four RPMs are introduced in the proper plane of the processor. The double image encryption system based on a nonlinear JTC in the FD increases the security of the system because there is a larger key space, and we can simultaneously validate two independent information signals (original images to encrypt) in comparison to previous similar proposals. The feasibility and performance of the proposed double image encryption and decryption system based on a nonlinear JTC are validated through computational simulations. Finally, we additionally comment on the proposed security system resistance against different attacks based on brute force, plaintext and deep learning.

Optical asymmetric JTC cryptosystem based on multiplication-division operation and RSA algorithm

The joint transform correlator (JTC) cryptosystem is a simple and practical optical cryptosystem. However, the anti-attack capability of JTC cryptosystem is still needed to be improved because of its linearity, and the identical key mask in both encryption and decryption also brings inconvenience and security risks in the key distribution and management. Aiming at overcoming these drawbacks, a novel optical asymmetric JTC cryptosystem is proposed in this paper. To design optical asymmetric JTC cryptosystem, a simple but effective trapdoor one-way function based on the image multiplication and division (IMD) operation is created for the first time to author’s knowledge. To improve the distribution and management of key mask in JTC cryptosystem, RSA algorithm is utilized to protect the structural parameters and geometric size of the structured spiral phase mask (SSPM), so the security of JTC cryptosystem can be enhanced simultaneously. The merits of our proposed optical asymmetric JTC cryptosystem, whose keys include a RPM public key, the RSA public key, the IMD private key and the RSA private key, are as follows: (1) the IMD operation is low in complexity and easy to be carried out with the aid of a time-varying noise image after the denoised joint power spectrum is obtained; (2) the keys in our proposal conform more closely to the basic agreement of asymmetric cryptosystem that have great advantages in the key distribution and management. Both simulation analysis and initial experimental results verified the correctness and feasibility of our proposal, which is provided with not only simplicity in configuration but also reliable security performance.

Optical asymmetric JTC cryptosystem based on binary phase modulation and image superposition-subtraction operation.

The joint transform correlator (JTC) cryptosystem is a simple and practical optical cryptosystem. But its identical key in both encryption and decryption brings security risks in the key distribution and management. To overcome these drawbacks, we first create a trapdoor one-way function based on image superposition and subtraction operation. Then combined with the one-way binary phase modulation, an optical asymmetric JTC cryptosystem is proposed in this paper. These two kinds of trapdoor one-way functions are not only effective and implementable, but also can greatly enhance the ability of our proposal to resist various attacks. In addition, we select the structured spiral phase mask (SSPM) controlled by its structural parameters as the key mask of the JTC cryptosystem to facilitate the key transmission. When the structural parameters of the SSPM are protected by the RSA algorithm during encryption and decryption, not only the security of the proposed cryptosystem can be enhanced, but also the key distribution and management will be improved. This also makes our proposal conform more closely to the basic agreement of the public key cryptosystem. Simulation analysis and initial experimental results verified the correctness and feasibility of our proposal.

Unmodulated fully-phase and shifted-phase encoded encryption key using Arnold transform and joint fractional Fourier transform correlator

We propose a nonlinear image encryption system using Arnold transform (ART) and a fully-phase encoded images as inputs to a nonzero-order joint transform correlator (JTC) in the fractional Fourier transform (FRFT) domain. Unlike other reported works, the fully-phase image along with two random-phase masks (RPMs) are introduced directly without linear phase modulation at the input plane of the JTC where the FRFT modulates this joint input image and produces the joint fractional power distribution (JFPD) at the output plane. It will be demonstrated that using modulating inputs in the optical setup makes the decryption scheme prone to error and leads to retrieving image failure. Further, a shifted-phase encoded key mask is applied in this proposal to achieve the non-zero order JFPD, which is adjusted by a nonlinear operation to guarantee a securely and high-quality retrieved ciphertext image. Furthermore, the proposed encryption scheme has four security keys: (i) two-random-phase masks, (ii) an ART frequency parameter, and (iii) a fractional order of the FRFT. It will be demonstrated that the decryption process is very sensitive to small variations of the ART frequency parameter, the fractional order of the FRFT, and the RPM. The cryptanalysis shows that the proposed encryption system is very invulnerable to Chosen plaintext (CPA), known plaintext (KPA), ciphertext only (COA) and brute force attacks. In addition, the robustness of the proposed scheme against noise and occlusion is presented using computer simulations.

Multiple Targets Recognition for Highly-Compressed Color Images in a Joint Transform Correlator

Multiple Targets Recognition for Highly-Compressed Color Images in a Joint Transform Correlator

Structured light based optical pattern recognition:Principle and technical progress

<p indent=0mm>Optical image recognition technology has attracted considerable attention due to its advantages, such as extensive information processing capacity, high-speed calculation, and advanced parallel processing. This technology also has various applications in security systems, remote sensing imaging, biomedical technology, and military scenarios. With the development of structured optical engineering technology, optical image recognition has gained new vitality in recent years. This paper describes two major optical image recognition correlators, the Vander Lugt Correlator and Joint Transform Correlator. We describe the progress of research on optical pattern recognition in the framework of linear optics, nonlinear optics, and quantum correlation. Our study also emphasizes how structured light engineering technologies can be incorporated into all-optical pattern recognition systems to accelerate technological developments.

Recognition method for Optical Multiple Channeled Joint Transform Correlation Based on Compression and Translation of Power Spectrum

Recognition method for Optical Multiple Channeled Joint Transform Correlation Based on Compression and Translation of Power Spectrum

P.101 Neurotic personal characteristics of gifted adolescents

We propose a binary image encryption method in joint transform correlator (JTC) by aid of the run-length encoding (RLE) and Quick Response (QR) code, which enables lossless retrieval of the primary image. The binary image is encoded with RLE to obtain the highly compressed data, and then the compressed binary image is further scrambled using a chaos-based method. The compressed and scrambled binary image is then transformed into one QR code that will be finally encrypted in JTC. The proposed method successfully, for the first time to our best knowledge, encodes a binary image into a QR code with the identical size of it, and therefore may probe a new way for extending the application of QR code in optical security. Moreover, the preprocessing operations, including RLE, chaos scrambling and the QR code translation, append an additional security level on JTC. We present digital results that confirm our approach.

Optical image encryption and authentication scheme based on partial joint power spectrum and phase-retrieval technique

In this paper, a novel optical image encryption and authentication scheme based on partial joint power spectrum (JPS) and phase-retrieval technique has been proposed. In the proposed encryption process, a pure amplitude spatial light modulator (SLM) is utilized to modulate and display the entire input plane comprised with the real-valued plaintext and the amplitude key while the random phase mask (RPM) merged with the plaintext could be provided by the ground glass in the practical setup. The entire input plane is regarded as the input of a joint transform correlator (JTC)-based encryption structure while the sub-block (partial JPS) recorded by the charged-couple device (CCD) is the output (ciphertext). Since only the sub-block is recorded in the encryption process, the size of the plaintext could be larger than that of the CCD in a certain degree, which is a major advantage comparing to the conventional JTC-based cryptosystem. In addition, since the size of the ciphertext is irrelative to the size of the plaintext, the security of location key in the entire plane has been enhanced. In addition, the location keys of the chosen sub-block used as the ciphertext are regarded as additional private keys, which enlarges the key spaces of the conventional JTC-based cryptosystem. In the proposed authentication process, the sub-block (ciphertext) is used as the partial amplitude constraint in the iterative process based on phase-retrieval technique and then the decoded image is authenticated by the nonlinear optical verification operator. It is the first time that the optical image encryption and authentication using partial JPS as the ciphertext has been proposed. Numerical simulation is carried out to validate the feasibility and effectiveness of the proposed scheme.

Second harmonic generation based joint transform correlator for human face and QR code recognitions

We propose a nonlinear joint transform correlator (JTC) based on a joint power spectrum via second-harmonic generation (SHG) in the Fourier domain. The fundamental waves of 1064 nm infrared light illuminate the images displayed by a single spatial light modulator. After SHG in a type-II potassium titanyl phosphate crystal in the Fourier domain, the second-harmonic wave of 532 nm visible light yields the correlation signal. We demonstrate the performance of our SHG-based JTC for human face recognition and quick response code recognition. Our work has the potential in various optical information processing applications such as infrared pattern recognition and remote sensing, security verification, target tracking, and optical computing.

Experimental optical encryption scheme for the double random phase encoding using a nonlinear joint transform correlator

We present a new experimental system for optical encryption using a nonlinear joint transform correlator (JTC) to implement the optical security technique of the double random phase encoding (DRPE). The DRPE, which is usually performed in a 4f-processor, encodes an image into a noisy distribution (encrypted image) by using two random phase masks (RPMs). In our experimental setup, the input plane of the JTC is fully encoded in phase and this plane contains two non-overlapping data functions (images). In the encryption step, the phase-encoded image to be encrypted and the two RPMs are placed in the input plane of the JTC with the purpose of obtaining the needed intensity distributions at the output plane to compute the encrypted image. The optical and numerical transformations are performed in the Fourier domain. A nonlinear operation is introduced to modify the joint power spectrum (JPS) of the JTC in order to reproduce exactly the same results of the DRPE. The experimental optical encryption scheme based on a three-step JTC is implemented by using an optoelectronic setup. The input plane of the JTC is optically implemented by means of a phase-only spatial light modulator (SLM). The decryption process is performed using a virtual optical system. Experimental and numerical results of the optical encryption and simulated decryption systems are presented, in order to show the feasibility of the proposed security system.

Image Encryption System Based on Joint Transformation Correlation and Ptychography

In this paper, a new image encryption system based on joint transformation correlation principle and ptycholographic iterative engine is proposed. When the encryption is performed, the original image can be divided into several parts by using the scanning movement of the probe. Each part is encrypted by the joint transformation correlation technology, and the ciphertexts are finally transmitted in the form of many encrypted images. The receiver uses the working principle of the joint transform correlator to decrypt and reconstructs the image by using the ptycholographic iterative engine, which can integrate multiple images with less information into one high-precision decrypted image. Computer simulations prove its possibility.

Optical encryption and authentication scheme based on phase-shifting interferometry in a joint transform correlator

In this paper, the effectiveness of the cryptosystem based on phase-shifting technique (PST) in a joint transform correlator (JTC) is evaluated. It is shown that the cryptosystem has some inherent drawbacks, for example, since the plaintexts are required to obtain the phase-shifting intensity patterns in the first phase extraction step, which means that the information of the plaintexts should be known by the authorized users before decryption processing. It seems impossible and paradoxical in the practical case. Moreover, the cryptosystem can only achieve binary plaintexts encryption while the inputs of this scheme cannot be the gray-scale or color images. To address these issues, we propose an encryption and authentication scheme based on PST in a JTC. By introducing a pre-processing operation including an intensity modulator based on histogram equalization and photon-counting (PC) operator, a photon-limited binary distribution of the plaintexts is obtained and used as the input of the cryptosystem. Due to this design, our proposed scheme can achieve encryption for different kinds of images such as binary, gray-scale and color images using same optical setup without any changes, which can simplify the optical implementation. Furthermore, a post-processing operator to extract phase information of encoded images and authenticate the decoded images is introduced. Since no useful information will be released from the photon-limited binary decoded images obtained using correct decryption keys and the interface of the database storing the plaintexts is only given to the authorized users, an additional security layer is established. This is the first time to report the use of binary intensity pattern in a scheme based on PSI in a JTC for secured verification of different images.

A Joint Transform Correlator Encryption System Based On Complex Amplitude Modulation for Grayscale Images

Aiming at the problem that the joint transform correlator (JTC) encryption system is difficult to perform experiments on encrypted grayscale images, a JTC encryption system based on complex amplitude modulation for grayscale images system is proposed. In this system, the complex amplitude modulation is implemented by means of single pixel hologram coding, so that the encryption of the grayscale image can be completed by using a single spatial light modulator with pure phase in the JTC encryption experiment.

In depth learning based method of denoising joint transform correlator optical image encryption system

There is serious noise interference in the decryption process of the joint transform correlator (JTC) optical encryption system, so the quality of the decrypted image cannot meet the accuracy requirements in most cases. The quality of decrypted image can be improved to a certain extent when the phase key is designed by the Gerchberg-Saxton algorithm and the iterative algorithm fuzzy control algorithm, but the complexity of the design process is inevitable and the quality of the decrypted image still needs improving. Recently, the in depth learning technology has attracted the attention of scholars in the fields of computer vision, natural language processing and optical information processing. In order to deal with the noise interference in the JTC optical encryption system, combining the current deep learning method, in this paper we propose a new denoising method for JTC optical image encryption system based on in depth learning, the dense modules are added into the generated network to enhance the reuse of feature information and improve the performance of the network. The latest self-attention mechanism area is added into the network to distinguish the weights of different channels and learn the relationship between channel and channel, so that the network can selectively strengthen the useful feature information but suppress useless feature information. The density module and the channel attention module are integrated into a DCAB synthesis module, which can effectively extract the image feature information and improve the performance of the network. The receptive field of the convolution kernel is enlarged by two down-sampling and the feature map is restored to its original size by two up-sampling. The VGG-19 is used to extract high-frequency details and texture features of images, meanwhile, the non-adversarial loss and mean-square error (MSE) loss are added into the loss function to reduce the difference among the image samples. The quality of noise-reduced images in this method are obviously better than that of the existing denoising algorithms by evaluating intuitive visual observation or SSIM (structural similarity), PSNR (peak signal to noise ratio) and MSE. The results of numerical calculation and simulation experiments show that this method can greatly eliminate the influence of noise on the JTC optical image encryption system, and effectively improve the effectiveness and feasibility of JTC optical image encryption system for high-quality image encryption.

边缘提取在图像相关识别中的应用及分析

边缘提取在图像相关识别中的应用及分析

Image Encryption System Based on a Nonlinear Joint Transform Correlator for the Simultaneous Authentication of Two Users

We propose a new encryption system based on a nonlinear joint transform correlator (JTC) using the information of two biometrics (one digital fingerprint for each user) as security keys of the encryption system. In order to perform the decryption and authentication in a proper way, it is necessary to have the two digital fingerprints from the respective users whose simultaneous authentication is pursued. The proposed security system is developed in the Fourier domain. The nonlinearity of the JTC along with the five security keys given by the three random phase masks and the two digital fingerprints of the two users allow an increase of the system security against brute force and plaintext attacks. The feasibility and validity of this proposal is demonstrated using digital fingerprints as biometrics in numerical experiments.