• Title, Summary, Keyword: Optical correlator

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Optical encryption system using random divided image and joint transform correlator (무작위 분할 영상과 결합변환 광 상관기를 이용한 암호화 시스템)

  • 최상규;서동환;신창목;김수중;배장근
    • Korean Journal of Optics and Photonics
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    • v.14 no.6
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    • pp.636-642
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    • 2003
  • We proposed the optical system using two divided halftone images to hide the original image and a joint transform correlator. The encryption procedure is performed by the Fourier transform of the product of each divided image by visual cryptography and the same random image which is generated by computer processing. As a result, we can obtain two Fourier divided images which are used as the encrypted image and the decrypting key, respectively. In the decryption procedure, both the encrypted image and the decrypting key are located on the joint input plane. Then the original image is reconstructed on a CCD camera which is located in the output plane. An autocorrelation term of joint transform correlator contributes to decrypt the original image. To demonstrate the efficiency of the proposed system, computer simulations and noise analysis are performed. The result show that the proposed system is a very useful optical certification system.

Volume holographic correlator for fingerprint recognition (지문 인식을 위한 체적 홀로그래픽 광상관기)

  • 이승현;김은수
    • Korean Journal of Optics and Photonics
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    • v.9 no.6
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    • pp.385-389
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    • 1998
  • In this paper, we propose an optical correlator system using volume holograms for database of matched filters. Optical correlator has high speed and parallel processing characteristics of optics. Matched filters are recorded into a volume hologram that can store data with high density, transfer them with high speed, and select a randomly chosen data element. The multiple reference images of database are prerecorded in a photorefractive crystal in the form of Fourier transform images, simply by passing the image displayed in a spatial light modulator through a Fourier transform lens. The angular multiplexing method for multiple holograms of database can be achieved by rotating the crystal by use of a step motor. Experimental results show that the proposed system can be used for the fingerprint recognition.

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A Study on the Optical Character Recognition using Optical Correlators Computer (광상관기를 이용한 컴퓨터용 광문자인식에 관한 연구)

  • 박현철;송우영;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.9 no.4
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    • pp.179-183
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    • 1984
  • Only K=$log_2$N reference patterns called principal components are sufficient to identify one out of N characters, calculated by computer and fablicated. An incogerent optical correlator is used for correlation coefficient measurements and it is shown that that this method has better discrimination ability that analog measuments using matched filter.

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Symbolic Substitution Based on Optical Correlator for Optical Parallel Addition with Redundant Binary Number (잉여 이진수 광병렬 가산을 위한 광상관 기호치환)

  • 노덕수;김정우;조웅호;김수중
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.1
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    • pp.269-280
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    • 1996
  • We proposed a symbolic substitution method based on an optical correlator for an optical parallel addition. In the proposed symbolic substitution method, we used redundant binary number of the symbolic substitution rules as a number system and chose MAC3E filter which had very low sidelobes and good correlation peak compared with SDF filter as the optical correlation filter. We encoeded input numbers property to increase the discrimination capability and divided inpt patterns into 5 groups of the same addition results to minimize the number of symbolic substitution rules. Through the computer simulation, we confirmed the proposed method was suitable to implement the optical parallel adder.

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Performance Evaluation of Data Archive System for High-Speed Saving of Correlated Result of Daejeon Correlator (대전상관기의 상관결과 고속저장을 위한 데이터아카이브 시스템의 성능시험)

  • Roh, Duk-Gyoo;Oh, Se-Jin;Yeom, Jae-Hwan;Oh, Chung-Sik;Yun, Young-Joo;Jung, Jin-Seung;Jung, Dong-Kyu
    • Journal of the Institute of Convergence Signal Processing
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    • v.15 no.2
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    • pp.55-63
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    • 2014
  • In this paper, we introduce the performance evaluation of data archive system for saving correlation result of Daejeon correlator with high-data rate. Daejeon correlator supports various correlation modes, but the speed of correlation result is affected by correlator according to the integration time in each mode. Maximum data rate of Daejeon correlator is 1.4GB/s in case of C1 mode with 25.6ms integration time. In this research, the performance evaluation of the proposed data archive system is conducted for saving correlation results connected with 4 10GbE optical cable with VCS (VLBI Correlation Subsystem), which is the core system of Daejeon correlator. For the experiments, the data archive system for 2 benders was selected and benchmark test was performed. In this paper, the developed data generation program of VCS correlation result file for benchmark test and evaluation results are described.

A Study on the Optical Pattern Recognition Using pSDF and Binary Joint Transform Correlator (pSDF와 이진 결합 변환 상관기를 이용한 광 패턴 인식에 관한 연구)

  • Jung, Chang-Kyoo;Cho, Dong-Rae;Gil, Sang-Keun;Park, Han-Kyu
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.11
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    • pp.111-118
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    • 1990
  • In this paper, pSDF-based referance image is realized. Using BJTC (binary joint transform correlator) as the spatial plane correlator, optical pattern recognition for interclass identification and interclass discrimination is performed. Computer simulation shows that the correlation performance of BJTC is superior to that of JTC. Experimental results using BJTC reveal that correlation peak intensity is constant within the error rang from $4.1{\%}\to\9.6{\%}$ in interclass identification and correlation peak intensity of one class is two times higher than that of the other class in interclass discrimination, which indicates its superiority in discrimination sensitivity.

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Shift and Noise Tolerance Encryption System Using a Joint Transform Correlator (결합 변환 상관기를 이용한 잡음 및 변이에 강한 암호화 시스템)

  • 서동환;김수중
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.7
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    • pp.499-506
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    • 2003
  • In this paper, we propose the shift and noise tolerance method using a virtual phase image and a joint transform correlator (JTC) architecture that can alleviate the need for an accurate optical axis alignment. An encrypted image is obtained by the Fourier transform of the product of a phase- encoded virtual image to camouflage the original one and a random phase image. Therefore, even if unauthorized users analyze the encrypted image, we can prevent the possibility of counterfeiting from unauthorized people using virtual image which dose not contain any information from the original image. We demonstrate the robustness to noise, to data loss and to shift of the encrypted image using a JTC in the proposed description technique.

3D Image Correlator using Computational Integral Imaging Reconstruction Based on Modified Convolution Property of Periodic Functions

  • Jang, Jae-Young;Shin, Donghak;Lee, Byung-Gook;Hong, Suk-Pyo;Kim, Eun-Soo
    • Journal of the Optical Society of Korea
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    • v.18 no.4
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    • pp.388-394
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    • 2014
  • In this paper, we propose a three-dimensional (3D) image correlator by use of computational integral imaging reconstruction based on the modified convolution property of periodic functions (CPPF) for recognition of partially occluded objects. In the proposed correlator, elemental images of the reference and target objects are picked up by a lenslet array, and subsequently are transformed to a sub-image array which contains different perspectives according to the viewing direction. The modified version of the CPPF is applied to the sub-images. This enables us to produce the plane sub-image arrays without the magnification and superimposition processes used in the conventional methods. With the modified CPPF and the sub-image arrays, we reconstruct the reference and target plane sub-image arrays according to the reconstruction plane. 3D object recognition is performed through cross-correlations between the reference and the target plane sub-image arrays. To show the feasibility of the proposed method, some preliminary experiments on the target objects are carried out and the results are presented. Experimental results reveal that the use of plane sub-image arrays enables us to improve the correlation performance, compared to the conventional method using the computational integral imaging reconstruction algorithm.