• Title, Summary, Keyword: 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.

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

  • 최상규;신창목;서동환;김수중;배장근
    • Proceedings of the Optical Society of Korea Conference
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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.

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

  • 이상이;김은수
    • Journal of the Korean Institute of Telematics and Electronics A
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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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A Study on Optical Information Processing using Volume Hologram (체적 홀로그램을 이용한 광정보처리 기술에 관한 연구)

  • Cho, Chong Duck;Kim, Kyu Tae
    • Journal of Korea Society of Digital Industry and Information Management
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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.

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

  • 전석희;유흥균;김규태;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.4
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    • pp.286-294
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    • 1990
  • The objective of this paper lies in presenting in theory an interpretation of how signals are detected from the real-time A/O correlator, and scrutinize by experimental processes, thereby to devise a method by which correlation function can be detected in a favorable way in time. An A/O system for real-time correlation function of two signals has been constructed. This optical correlator when at work in intensity modulation mode by acousto- optic device renders higher output signal to noise ration, as compared with the traditional optical signal detection, has simple system as compared with existing optical correlator in amplitude modulation mode.

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

  • 김성완;김철수;김종찬;김종윤;이승희;김수중
    • Journal of the Korean Institute of Telematics and Electronics D
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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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Image Encryption and Decryption Using SA Algorithm and Optical Correlator System (SA 알고리듬과 광 상관 시스템을 이용한 영상 암호화 및 복호화)

  • 김철수;조창섭
    • Journal of Korea Multimedia Society
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    • v.7 no.3
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    • pp.349-356
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    • 2004
  • In this paper, a practical image security system using SA algorithm and 4-f optical correlator system is proposed. The encrypted image and key image with binary phase components are generated using an iterative SA algorithm. a decrypted image is found through the correlation of the encrypted and key images using 4-f optical correlator system. The encrypted and key images are consisted of binary phase components. So, it is easy to implement the optical security system using the proposed technique. And if we fix the encrypted image in the optical security system and change the key images, we get different images, so it is possible to apply to the distinguished authorization system using different key images. Computer simulations show that despite the binary phase components of the two images(encrypted and key image), decrypted images are generated.

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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.