• 제목, 요약, 키워드: Optical correlator

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Image Blurring Estimation and Calibration with a Joint Transform Correlator

  • Jeong, Man Ho
    • Journal of the Optical Society of Korea
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    • v.18 no.5
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    • pp.472-476
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    • 2014
  • 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.

분할 영상과 결합변환 상관기를 이용한 주파수 영역에서의 광 암호화 시스템 구현 (Fourier-Plane Encryption System using Divided Images and a Joint Transform Correlator)

  • 최상규;신창목;서동환;김수중;배장근
    • 한국광학회:학술대회논문집
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    • pp.58-59
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    • 2003
  • We propose the optical encryption system using two divided image to hide the original image and a joint transform correlator. The encryption procedure is performed by the Fourier transform of the product of each phase encoded image (divided phase images) and the same random phase image which is generated by computer processing. An autocorrelation term of joint transform correlator contributes to decrypt the original image. This system will be used in optical certification.

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Binary Nonlinear Joint Transform Correlator with Sinusoidal Iterative Filter in Spectrum Domain

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.4
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    • pp.357-362
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    • 2010
  • The joint transform correlator (JTC) has been the best known technique for pattern recognition and identification. This paper proposes a new technique of fringe adjustment by adopting a sinusoidal amplitude-modulated iterative filter convolved with an interference fringe pattern in the joint power spectrum (JPS) domain. The comparison of our new technique and other techniques is presented to show that the newly proposed technique can successfully improve both the correlation peaks and the peak signal-to-noise ratio (PSNR). Simulated results of enhanced interference fringes are also presented.

New Random and Additional Phase Adjustment of Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.14 no.2
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    • pp.90-96
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    • 2010
  • Joint transform correlator (JTC) has been the most suitable technique for real time pattern recognition. This paper proposes a new phase adjustment which adopts two steps of random phase adjustment in the spatial domain and additional phase adjustment in the Fourier domain. Simulated results are presented to show the optimum condition of the phase adjustment and the effect on the correlation peaks, the peak signal-to-noise ratio and the level of discrimination.

상관신호의 판별력 개선을 위한 광 BPEFTC 시스템 (Optical Binary Phase Extraction Joint Transform Correlator System for Improving the Correlation Discrimination)

  • 이상이;김은수
    • 전자공학회논문지A
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    • v.31A no.6
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    • pp.78-87
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    • 1994
  • In this paper, a binary phase extraction joiont transform correlator (BPEJTC)system is proposed as a new phase-type optical correlator in which the correlation errors and DC component are dramtically reduced and optical efficiency and correlation performance are also improved by reconstructing the joint transform power spectrum (JTPS) of the conventional joint transform correlator (JTC)system form which the autocorrelation and crosscorrelation siganls generated in each self-plane are removed, and the binary phase function is extracted from the phase value of the reconstructed JTPS. Through some computer simulation and optical experimental results, the possibility of the implementation of the real-time multi-target tracking and recognition system is also suggested.

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체적 홀로그램을 이용한 광정보처리 기술에 관한 연구 (A Study on Optical Information Processing using Volume Hologram)

  • 조종덕;김규태
    • 디지털산업정보학회논문지
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    • v.5 no.2
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    • pp.51-76
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    • 2009
  • In this paper, a new hybrid opto-digital multiple information hiding and real-time extracting system was suggested and implemented using a volume holographic optical correlator. The multiple information hiding system in which the multiple information can be hided in an arbitrary cover image was digitally implemented by using the combination of pseudo random sequence and Hadamard matrix. In addition, a real-time optical extraction system in which the hided multiple information in a cover image can be extracted in real-time was implemented by using a volume holographic optical correlator. In the VanderLugt-type holographic optical correlator used in this experiment, the multiful matched spatial filters corresponding each of the hided informations were recorded in a photorefractive crystal by using the moving window-based angular multiplexing scheme.

A/O 광상관기의 실시간 신호처리 (Real-Time Signal Processing of A/O Correlator)

  • 전석희;유흥균;김규태;박한규
    • 한국통신학회논문지
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    • v.15 no.4
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    • pp.286-294
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    • 1990
  • 본 논문은 A/O광산관기의 실시간 신호 처리에 대하여 이론적으로 분석하고 실험을 통하여 시간적으로 두 신호의 상관함수를 얻는 방법을 연구하였다. 강도변조모드로 동작하는 본 광상관기는 종래의 광상관기에 비해 SNR을 높일 수 있었고 진폭변조모드로 동작하는 기존의 광상관기에 비해 시스템 구성이 간단하고 신호검출이 용이함을 보였다.

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변이불변 특성이 개선된 광굴절 상관기를 이용한 실시간 광 패턴인식 시스템 구현 (Implementation of real-time optical pattern recognition system using a photorefractive correlator with improved shift-invariant property)

  • 김성완;김철수;김종찬;김종윤;이승희;김수중
    • 전자공학회논문지D
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    • v.35D no.3
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    • pp.63-69
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    • 1998
  • In this paper, a new input method is proposed to improve shift-invariant property of a photorefractive correlator andwe implemented real-time optical pattern recognition system using it. In the conventional photorefractive correlator, it is vrey difficult to satisfy the Bragg condition in the pattern recognition process. So, correlation peak is decreased heavily for the shift of input image. If a liquid crystal television(LCTV) without an anlyzer is used as input device, we can get the correlation result regardless of shift of input image because beam path is not changed during storage of holographic filter and correlation process. Also recording time of a holographic matched filter in photorefractive crystal is reduced and the correlation peak is increased because incident beam on the LCTV is transmitted completely. Therefore total optical efficiency is improved. We compared and analyzed the correlation results of proposed photorefractive correlator by computer simulation and optical experiment. We used a BaTiO$_{3}$ single crystal which has high diffraction efficiency in optical experiment.

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SA 알고리듬과 광 상관 시스템을 이용한 영상 암호화 및 복호화 (Image Encryption and Decryption Using SA Algorithm and Optical Correlator System)

  • 김철수;조창섭
    • 한국멀티미디어학회논문지
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    • v.7 no.3
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    • pp.349-356
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    • 2004
  • 본 논문에서는 SA(simulated annealing) 알고리듬에 기반한 4-f 광 상관 시스템을 이용하여 실제적인 영상 보안 시스템을 제안하였다. 반복적인 SA알고리듬을 이용하여 이진 위상 성분을 갖는 암호화된 영상과 키 영상을 얻고, 4-f 광 상관 시스템을 이용하여 암호화된 영상과 키 영상과의 상관을 통해 복호화된 영상이 구해진다. 제안된 방법에서는 암호화된 영상 및 키 영상이 이진 위상 성분으로 구성되므로 광 보안 시스템을 구현하기 쉬운 장점이 있다. 그리고 만약 암호화된 영상을 암호화 시스템내에서 고정시키고, 키 영상 정보만을 달리 하면 서로 다른 영상을 복호화할 수 있으므로 차별화된 인증시스템에 응용할 수 있는 장점도 있다. 컴퓨터 시뮬레이션 결과는 두 영상(암호화 및 키 영상)의 이진 위상 성분에도 불구하고, 복호화영상이 생성됨을 보여준다.

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Analysis of Fingerprint Recognition Characteristics Based on New CGH Direct Comparison Method and Nonlinear Joint Transform Correlator

  • Jeong, Man-Ho
    • Journal of the Optical Society of Korea
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    • v.13 no.4
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    • pp.445-450
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    • 2009
  • Fingerprint recognition using a joint transform correlator (JTC) is the most well-known technology among optical fingerprint recognition methods. The JTC method optically compares the reference fingerprint image with the sample fingerprint image then examines match or non-match by acquiring a correlation peak. In contrast to the JTC method, this paper presents a new method to examine fingerprint recognition by producing a computer generated hologram (CGH) of those two fingerprint images and directly comparing them. As a result, we present some parameters to show that fingerprint recognition capability of the CGH direct comparison method is superior to that of the JTC method.