• Title, Summary, Keyword: Optical correlator

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A study on JTC optical encryption system using binary CGHs (Binary CGH를 사용한 JTC 광암호화 시스템 연구)

  • 주성현;정만호
    • Korean Journal of Optics and Photonics
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    • v.14 no.5
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    • pp.491-497
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    • 2003
  • In this paper, an optical encryption system using binary key code based on the joint transform correlator (JTC) is considered. The binary key code is synthesized by using a design technique of the pixel-oriented Computer Generated Holograms (CGHs). The independence and efficiency of the binary encryption key are investigated through computer simulation. To test the efficiency of the encryption system using binary key code, a holographic encryption system is constructed, and the experimental results prove that our holographic encryption system has high ability.

A Joint Transform Correlator Encryption System Based on Binary Encoding for Grayscale Images

  • Peng, Kaifei;Shen, Xueju;Huang, Fuyu;He, Xuan
    • Current Optics and Photonics
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    • v.3 no.6
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    • pp.548-554
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    • 2019
  • A binary encoding method for grayscale images is proposed to address their unsatisfactory decryption results from joint transform correlator (JTC) encryption systems. The method converts the encryption and decryption of grayscale images into that of binary images, and effectively improves decrypted-image quality. In the simulation, we replaced unencoded grayscale images with their binary encoded counterparts in the JTC encryption and decryption processes, then adopted a median filter to suppress saturation noise while keeping other settings unchanged. Accordingly, decrypted-image quality was clearly enhanced as the correlation coefficient (CC) between a decrypted image and its original rose from 0.8237 to 0.9473 initially, and then further to 0.9937, following the above two steps respectively. Finally, optical experimental results confirmed that the proposed encryption system works correctly.

Color Pattern Recognition with Recombined Single Input Channel Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.15 no.2
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    • pp.140-145
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    • 2011
  • Joint transform correlator (JTC) is a well known tool for color pattern recognition for a color image. Color images have red, green and blue components, thus in conventional JTC, three input channels of these color components are necessary for color pattern recognition. This paper proposes a new technique of color pattern recognition by decomposing the color image into three color components and recombining those components into a single gray image in the input plane. This new technique needs single input channel and single output CCD camera, thus a simple JTC can be used. We present various kinds of simulated results to show that our newly proposed technique can accurately recognize and discriminate color differences.

Coded Single Input Channel for Color Pattern Recognition in Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.15 no.4
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    • pp.335-339
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    • 2011
  • Recently, we reported a single input channel joint transform correlator for the color pattern recognition which decomposes the input color image into three R, G, and B gray components and adds those components into a single gray image in the input plane. This technique has the merit of a single input channel instead of three input channels. However, we found this technique has some problems with discrimination impossibility in the case of a simple primary color pattern which results in the same gray level through the addition process. Thus, we propose a modified coding technique which selectively recombines the decomposed three R, G, and B gray components instead of the simple adding process. Simulated results show that the modified coding technique can accurately discriminate a variety of kinds of color images.

New Iterative Filter for Fringe Adjustment of Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.1
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    • pp.33-37
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    • 2010
  • The joint transform correlator (JTC) has been the best known technique for pattern recognition and identification. The JTC optically compares the reference image with the sample image then examines match or non-match by acquiring a correlation peak. However, the JTC technique has some problems such as weak correlation discrimination and noise which originates from the interference fringes in the Fourier transform plane. In order to solve these problems, this paper proposes a new technique of modifications of the interference fringes by adopting special iterative filters. Experimental results are presented to show that the proposed technique can successfully improve the correlation peaks and the level of discrimination.

A Study on the Optical Pattern Recognition using pSDF and Nonlinear Correlator (pSDF와 비선형 상관기를 이용한 광패턴 인식에 관한 연구)

  • 정창규;임종태;김경태;박한규
    • Korean Journal of Optics and Photonics
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    • v.1 no.2
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    • pp.130-134
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    • 1990
  • In this paper, pSDF-based referance image is reahzed. Using BJTC(binary joint transform correlator) as nonlinear correlator, optical pattern recognition for interclass discrimination is performed. Experimental results show that correlation peak intensity of one calss is two times higher than that of the other class, which indicates its superiority in discrimination sensitivity.

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A Study on Signal Detections of Optical Signal Correlator using AOD/CCD (AOD/CCD 를 이용한 광신호 상관기의 신호검출에 관한 연구)

  • Kim, Kyung-Tae;Oh, Chang-Suk;Park, Han-Kyu
    • Proceedings of the KIEE Conference
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    • pp.94-97
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    • 1987
  • An acousto optic correlator system for performing real-time correlation of two signals is constructed. It uses AOD is described. The statistical analysis for correlator's output SNR is presented and experimental procedure for implemention of this technique are result shown. Since the correlation intergration is performed in time rather than space, the SNR of this system can be greatly improved.

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A Study on the Moving Traget Tracking System using Joint Transform Correlator (JTC를 이용한 이동 표적 추적 시스템에 관한 연구)

  • 이상인;서춘원;양성현;이기서;김은수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.7
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    • pp.749-757
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    • 1992
  • In this paper, as a more effective approach for maneuvering target tracking a realtime optical tracking system based of optical JTC(Joint Transform Correlator) which is capable of transforming the massive input target data into a few correlation peaks is implemented. And for real-time implementation the high resolution LCD(Liquid Crystal Display) spatialight modulator is used to construct the optical JTC system, and the mean binarization method is used to reduce the effects of background noises on correlation signal. From the good experimental results on maneuvering targets, the possibility of real-time moving target tarcking system based on optical JTC is a suggested.

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Optical Visual Cryptography based on Binary Phase Exctraction JTC (BPEJTC를 이용한 광 비쥬얼 크립토그래피)

  • 이상이;이승현
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.8
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    • pp.589-597
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    • 2003
  • Visual cryptography made it possible to decrypt thresholding scheme with not digital system but human vision system. This method, however, has some limit in it. Optical visual cryptography was proposed which used laser instead of human eyesight. As a result, it was possible to adapt cryptography to optical system. However, it also had some difficulties because it did not overcome the existing problem of visual cryptography completely. These problems occurred in the process of transferring data processing system from visual to optics. Therefore, it is appropriate to approach these problems in terms of optics. This paper analyzes the level of noise and the security characteristics for optical visual cryptography in terms of frequency based on joint transform correlator.

Effects of JPEG Compression on Joint Transform Correlator

  • Widjaja, Joewono;Suripon, Ubon
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1662-1665
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    • 2004
  • A real-time joint transform correlator by using JPEG-compressed reference images is proposed as practical solution to storage problem and improvement of processing time of automatic target recognition system [1]. Effects of compression on recognition performance of join transform correlator are quantitatively investigated under situations where the target is suffered from noise and has contrast difference with respect to the reference. Two images with different spatial-frequency contents and contrast were used as the test scenes. The simulation results show that, the recognition performance of joint transform correlator by using the compressed reference images with high spatial-frequency components is more sensitive to noise and contrast difference than the low spatial-frequency image.

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