Joint Transform Research Articles

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.

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

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.

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.

Optical Image Encryption Using a Nonlinear Joint Transform Correlator and the Collins Diffraction Transform

The Collins diffraction transform (CDT) describes the optical wave diffraction from the generic paraxial optical system. The CDT has as special cases the diffraction domains given by the Fourier, Fresnel and fractional Fourier transforms. In this paper, we propose to describe the optical double random phase encoding (DRPE) using a nonlinear joint transform correlator (JTC) and the CDT. This new description of the nonlinear JTC-based encryption system using the CDT covers several optical processing domains, such as Fourier, Fresnel, fractional Fourier, extended fractional Fourier and Gyrator domains, among others. The maximum number of independent design parameters or new security keys of the proposed encryption system using the CDT increases three times in comparison with the same encryption system that uses the Fourier transform. The proposed encryption system using the CDT preserves the shift-invariance property of the JTC-based encryption system in the Fourier domain, with respect to the lateral displacement of both the key random mask in the decryption process and the retrieval of the primary image. The viability of this encryption system is verified and analysed by numerical simulations.

A Multi-User Encryption and Authentication System Based on Joint Transform Correlation

Optical image encryption technology based on joint transform correlation (JTC) has attracted increasing attention from researchers. We propose a multi-user secure communication system based on the special properties of JTC. Multiple users utilize their own fingerprints to encrypt the plain-text in the encryption process, and each user must be first authenticated at the beginning of the decryption process. Only users with legitimate identities can perform the decryption process, whereas unauthorized users with false identities cannot, so the security of the system is greatly improved. Furthermore, we propose a multi-user double-image encryption method, which can better meet the needs of different security environments. Considering the possibility of overlapping images at the output end, we prove that a JTC-based image encryption system can avoid overlapping images at the output when the distance between the input images is 3W (W is the side length of a square image), which provides a theoretical foundation for further research. Finally, a numerical simulation demonstrates the effectiveness and feasibility of the proposed idea.

Precise Position Detection of Linear Motor Movers Based on Extended Joint Transformation Correlation

The extended joint transformation correlation (EJTC) algorithm is proposed in this paper to meet the high-precision and anti-interference requirements of linear motor mover position measurement. An image measurement system for linear motor mover position is established. Stripe image movement sequences are captured using a high-speed camera. First, the image is preprocessed using a bilateral filtering method. Second, the joint power spectral function of adjacent stripe images is obtained on the basis of the joint transform correlation method. The zero-order diffraction peaks are eliminated, and interference from cross-correlated peak side lobes is avoided. Third, subpixel positioning is obtained using the oversampled discrete Fourier transform. Finally, the actual displacement of the stripe images can be obtained by combining the system calibration coefficients. An experimental measurement platform for a linear motor mover is established to verify the validity of the EJTC algorithm. The EJTC shows high measurement accuracy and strong anti-interference ability.

Research on the Development of Large Scale Face Recognition Technology Based on Optoelectronic Hybrid Joint Transform Correlator

Research on the Development of Large Scale Face Recognition Technology Based on Optoelectronic Hybrid Joint Transform Correlator

Pattern Recognition Based on YIQ Colour Space with Simulated Annealing Algorithm and Optoelectronic Joint Transform Correlation

For pattern recognition on various views of the interested colour object, we adopt the YIQ colour space when using simulated annealing algorithm to design the template matching function. Joint transform correlation is devoted for recognition of colour targets. Quantized reference functions are designed for the purpose of display on liquid crystal spatial light modulators. Each reference function is trained with true class images rotated in-plane at 2 degrees intervals between -14 degrees and 14 degrees. Numerical result shows that, generally, YIQ space outperforms conventional RGB space. Normal 0 0 2 false false false EN-US ZH-TW X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:表格內文; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri,sans-serif; mso-bidi-font-family:Times New Roman;}

Digital Image Watermarking Based On Joint (DCT-DWT) and Arnold Transform

The researcher has adopted a digital watermarking technique which operates in the frequency domain: a hybrid watermarking scheme based joint discrete wavelet transform – discrete cosine transform – (DWT-DCT). Its main objective is to test whether this technique can withstand attacks (its robustness) and invisibility (its imperceptibility), achieved by taking DCT of the DWT coefficients of the LL mid-frequency sub-bands from its band. To ensure security, the secret code (watermark) is scrambled using the Arnold transformation which is embedded in the original host image; only gray-scale digital images are used. The results of this research reveal that the secret code (watermark) is strong enough against threats (noise). Comparative results are measured using signal-tonoise ratio criterions, mean square error and normalized cross correlation. Simulated experimentation is done in Matlab.

基于改进联合变换相关算法的航空序列影像位移测量

基于改进联合变换相关算法的航空序列影像位移测量

Application of Simulated Annealing for Color Pattern Recognition to Hybrid Optoelectronic Joint Transform Correlator

For invariant pattern recognition, a method using simulated annealing algorithm is introduced. Near optimal quantized reference functions are designed to be displayed on liquid crystal spatial light modulators. Mach-Zehnder joint transform correlator is adopted as the system for recognition of color targets. From numerical results, the optoelectronic pattern recognition system with simulated annealing algorithm shows a promising capability.

Application of Differential Transform Method for Estimating Thermal Cycle Developed in GTA Welding of High Carbon Steel Joints

This article reveals a detailed study of temperature cycle formed during Gas Tungsten Arc welding of high carbon steel (AISI 1090) butt joints. Experimental work has been carried out to estimate the temperature distribution along fusion boundary to longitudinal direction of the weldment by mounting thermocouples on the plate along with Data Acquisition System. Heat flux distribution due to moving point heat source has been demonstrated by implementing Gaussian surface heat flux and Angular Torch model. Cooling rate has predicted by application of Adams cooling rate equation. Conduction-convection phenomena plays dominant role for evaluating heat loss from the weld joint and Differential Transform Method (DTM) has been applied to judge non-dimensional temperature distribution. Analytical studies has shown well agreement with experimental temperature distribution.

Image Blurring Estimation and Calibration with a Joint Transform Correlator

The Joint Transform Correlator (JTC) has been the most suitable technique for real time optical pattern recognition and target tracking applications. This paper proposes a new application of the JTC system for an analysis of the blurring effect of the optical images caused by a defocused lens. We present the relation between the correlation peak, optical transfer function (OTF), and the amount of blurring caused by focusing error. Moreover, we show a possibility of calibrating the blurred image by simply measuring the correlation peak.

Location Technology of Correlation Peaks Based on Joint Transform Correlator

By comparing the similarity of their contour information, hybrid photoelectric joint transform correlator (JTC) is used to recognize the specific target. An effective method to increase the recognition rate is to extract the contour information of target and template and decrease the noise interference in image background. The principle of joint transform correlator is given in this paper. To increase the recognizing rate, a mask algorithm is presented, with which the coordinate of the correlation peaks can be located precisely. Before the mask algorithm, edge extraction with Robert operator is carried out to enhance the target contour information and reduce the background noise. Amounts of experiments prove the mask algorithm can locate the correlation peaks precisely. As an example, an experimental result is given with a car as the detected target. The coordinate of this car is (362, 438). Experimental results confirm the feasibility and effectiveness of the mask algorithm.

Co-channel Interference Suppression for Homo-type Radars Based on Joint Transform Domain and Time Domain

Co-channel Interference Suppression for Homo-type Radars Based on Joint Transform Domain and Time Domain

Athermal Design of Infrared Telephoto Used in Joint Transform Correlator

On the basis of optical correlation detection, joint transform correlator(JTC) is widely used in military, aviation and intelligentization and so on. It has the advantages of great flexibility and high precision of recognition. The optical system is applied to receive the infrared radiation of the target. Athermalization is the key to stabilizing the optical performance with respect to off-design temperature. Therefore, the image quality of optical system in different temperatures plays an important role in JTC. In order to improve the environmental adaptability of JTC, the infrared telephoto system with high image quality and high performance-price ratio is designed for wavelength 8μm～12μm to detect target in a large range of temperature. This telephoto lens is composed of four refractive lenses. Three materials, zinc selenide, germanium and zinc sulfide are used to compensate for the temperature. The focal length is 200 mm, the relative aperture is 1:3, and the field of view is 6.4°. This system has the characteristics of small volume and compact structure. The optical system image quality is evaluated with ZEMAX optical design software. The results have shown that MTFs in the range of -40°C to +60°C are all closed to the diffraction limited curve. The spot diagram RMS radius of each field is closed to the Airy disk radius. The system meets the requirements of technical specification and improves the ability of JTC in target tracking and recognition.