• Title/Summary/Keyword: 디지털광학방법

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누구나 쉽게 배울 수 있는 실전 사진촬영 (5) - 사진 촬영에 실패하지 않는 법

  • Gwak, Jung-Geun
    • The Optical Journal
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    • s.119
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    • pp.66-68
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    • 2009
  • 기술적으로 실패하는 사진의 유형을 보면 몇 가지 되지 않는다. 가장 많은 것이 사진이 흔들리는 경우이고 두 번째가 사진의 밝기(노출)가 맞지 않는 경우이며 세 번째가 핀트가 맞지 않는 경우인데 콤팩트 디지털카메라의 경우 핀트가 안 맞는 사진을 찍기가 더 어려운 상황이 더 많다. 사진촬영을 하면서 실패한 사진을 찍고 싶은 사람은 없겠지만 몇 년을 찍어도 사진이 잘 나오지 않는다면 그 이유는 간단하다. 자신의 실패를 뒤돌아보지 않든가 실패한 사진에 대해 별로 안타까움이 없는 사람일 것이다. 이번 호에서는 사진에 실패하지 않는 방법을 알아보자.

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A Color interpolation of Tongue Image (설진 영상의 색상 보정)

  • 김지은;박경모;박승옥;김홍석
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.07a
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    • pp.78-79
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    • 2003
  • 설진(舌診)은 한의학에서 망진(望診)의 한 분야로, 환자의 설질(舌質)과 설태(舌苔)의 변화를 관찰함으로써 질병을 진찰하는 방법이다. 임상에서 설진은 의사들의 주관적인 지식과 경험에 의해서 결정되며, 광원이나 주변 환경의 밝기의 차와 같은 외부적인 요인에 의해서 영향을 받는다. 또한 진단의 결과들은 정량적으로 저장, 관리되고 있지 않다. 그러므로 설진의 조직적이고 정량적인 진단 표준을 제공하고, 객관적인 설 진단법을 구축하기 위해서 디지털화된 설진시스템의 개발이 필요하다. (중략)

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모아레 광간섭에 의한 금형 형상의 삼차원 자동측정과 CAD/CAM과의 연계

  • 김승우
    • Journal of the KSME
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    • v.32 no.2
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    • pp.175-183
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    • 1992
  • 모아레토포그라피를 이용한 금형제작을 위한 클레이모형(clay model)의 3차원 형상측정을 위한 방법이 제시되었다. 그리고 모아레무늬를 해석하는 방법이 제시되어 클레이모형의 형상을 측정 하였고 디지털영상처리기법을 사용하는 일련의 과정을 통해 3차원 형상을 재현하였다. IBM PC/386과 CCD 카메라를 사용하여 실험한 결과 0.005mm의 분해능을 가지며 측정속도가 5분 가량이 소요되었다. 따라서 광학적방법이 접촉식 디지타이징을 이용하였을 경우 발생하는 많은 문제점 등을 효율적으로 보완할 수 있다. 그리고 품질검사를 자동화할 수 있는 방법을 제시하 였고 기존의 모아레토포그라피가 가지는 어려움을 극복하기 위하여 새로운 방법인 주사식 모아 레토포그라피를 제시하였다.

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Aspheric Lens Measurements by Digital Holographic Microscopy and Liquid (액체와 Digital Holographic Microscopy을 이용한 비구면 렌즈 측정 연구)

  • Kim, Doocheol;Shin, Sanghoon;Yu, Younghun
    • Korean Journal of Optics and Photonics
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    • v.24 no.6
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    • pp.318-323
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    • 2013
  • Digital holographic microscopy allows optical path difference measurement. Optical path difference depends on both the refractive index and the morphology of the sample. When interference fringes are very closely spaced, the phase data contain high frequencies where $2{\pi}$ ambiguities cannot be resolved. The immersion testing method, which is a transmission test while the sample is immersed in liquid, is very effective in reducing high frequency fringes in transmission measurements so that large dynamic range testing is possible for a non-null configuration. We developed a digital holographic microscope using liquid that can measure the high numerical aperture aspheric morphology of a sample. This system provides highly precise three-dimensional information on the sample. By improving the experimental method, choosing liquids which have similar refractive index to the sample, we can measure more accurate three-dimensional information on the samples.

Retrieval of Atmospheric Optical Thickness from Digital Images of the Moon (월면 디지털 영상 분석을 이용한 대기 광학두께 산출)

  • Jeong, Myeong-Jae
    • Korean Journal of Remote Sensing
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    • v.29 no.5
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    • pp.555-568
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    • 2013
  • Atmospheric optical thickness during nighttime was estimated in this study using analysis on the images of the moon taken from commercial digital camera. Basically the Langely Regression method was applied to the observations of the moon for the cloudless and optically stable sky conditions. The spectral response functions for the red(R), green(G), and blue(B) channels were employed to derive effective wavelength centers of each channel for the observations of the moon, and the correspondent Rayleigh optical thickness were also calculated. Aerosol optical thickness (AOT) was calculated by subtracting Rayleigh optical thickness from the atmospheric optical thickness derived from the Langley regression method. As there are only handful of nighttime AOT observations, the AOT from the moon observations was compared with the AOT from sun-photometers and the MODIS satellite sensor, which was taken several hours before the moon observations of this study. As a result, the values of AOT from moon observations agree with those from sun-photometers and MODIS within 0.1 for the R, G, B channels of the digital camera. On the other hand, ${\AA}$ngstr$\ddot{o}$m Exponent seems to be subject to larger errors due to its sensitiveness to the spectral errors of AOT. Nevertheless, the results of this study indicate that the method reported in this study is promising as it can provide nighttime AOT relatively easily with a low cost instrument like digital camera. More observations and analyses are warranted to attain improved nighttime AOT observations in the future.

Optical Encryption of Binary Information using 2-step Phase-shifting Digital Holography (2-단계 위상 천이 디지털 홀로그래피를 이용한 이진 정보 광 암호화 기법)

  • Byun, Hyun-Joong;Gil, Sang-Keun
    • Korean Journal of Optics and Photonics
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    • v.17 no.5
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    • pp.401-411
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    • 2006
  • We propose an optical encryption/decryption technique for a security system based on 2-step phase-shifting digital holography. Phase-shilling digital holography is used for recording phase and amplitude information on a CCD device. 2-step phase-shifting is implemented by moving the PZT mirror with phase step of 0 or ${\pi}/2$. The binary data and the key are expressed with random code and random phase patterns. The digital hologram is a Fourier transform hologram and is recorded on CCD with 256 gray level quantization. We remove the DC term of the digital hologram fur data reconstruction, which is essential to reconstruct the original binary input data/image. The error evaluation fer the decrypted binary data is analyzed. One of errors is a quantization error in detecting the hologram intensity on CCD, and the other is generated from decrypting the data with the incorrect key. The technique using 2-step phase-shifting holography is more efficient than a 4-step method because 2-step phase-shifting holography system uses less data than the 4-step method for data storage or transmission. The simulation shows that the proposed technique gives good results fur the optical encryption of binary information.

Design and Implementation of Fugitive Dust Measurement System using Optical Method (광학기법을 이용한 비산 먼지 측정 시스템의 설계 및 구현)

  • Chae-Hoon, Ban;Hyun-Gun, Son
    • The Journal of the Korea institute of electronic communication sciences
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    • v.17 no.6
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    • pp.1237-1242
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    • 2022
  • Fugitive dust, which accounts more than 50% of fine dust, is an air pollutant, that is generated by a lot in construction work(29.5%) and the law provides standards for facility installation and measures to control this. However, small-scale construction sites are not subject to management standards, and the law to measure and manage fugitive dust generated from construction sites is insufficient. In this paper, we designed and implemented the method to easily measure and monitor fugitive dust using the digital optical method for turbidity of dust. We presented the method to measure the turbidity of fugitive dust using the digital optical method and measured the actual turbidity of fugitive dust at the construction sites after implementing the fugitive dust measurement system.

A Study on Two-wavelength Digital Holography Using the Fresnel-Bluestein Transform (프레즈넬-불루스타인 변환을 이용한 2파장 디지털 홀로그래픽 연구)

  • Shin, Sanghoon;Kim, Doocheol;Yu, Younghun
    • Korean Journal of Optics and Photonics
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    • v.23 no.6
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    • pp.251-254
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    • 2012
  • Dual-wavelength holography has a better axial range than single-wavelength holography, allowing unambiguous phase imaging. The size of a reconstructed image depends on the reconstruction distance and wavelength. The two phase image sizes of different wavelength holograms should be the same in order to apply dual-wavelength holography. The Fresnel-Bluestein transform method is proposed to eliminate the dependence on the reconstruction distance and wavelength. We found that the Fresnel-Bluestein transform is very useful for making different reconstructed image sizes experimentally. Also we applied the Fresnel-Bluestein transform to make the same reconstruction image size in dual wavelength holography.

Study on Digital Holography with Conjugated Hologram (복소공액 홀로그램을 이용한 디지털 홀로그래피 연구)

  • Shin, Sang-Hoon;Kim, Doo-Cheol;Yu, Young-Hun
    • Korean Journal of Optics and Photonics
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    • v.21 no.4
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    • pp.146-150
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    • 2010
  • In this paper we have applied phase conjugated holographyto DHM (digital holography microscopy) to remove phase aberration and noise. Generally,digital holographyincludes the phase information of the object, phase aberration terms introduced by the measurement system and noise terms (DC term and twin images). These aberrations and noise terms decrease the quality of the reconstructed phase image. We could obtain a conjugated hologram which includes only phase information of object. Experimentally we show that distortion of image and aberration of phase in a measurement system are removed using the conjugation hologram.

Development of Chameleonic Multi-Surface Display with Dynamic Projection Mapping (동적 실물영상투사 카멜레온(다변) 멀티 서피스 콘텐츠 연구)

  • Hong, Sung-Dae
    • Journal of Digital Contents Society
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    • v.18 no.1
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    • pp.123-132
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    • 2017
  • The physical display technology is the ultimate display technology that human beings aspire, and the world makes use of laser, plasma and reflector plate. Besides, technology development of binocular stereoscopic display has been actively progressed, but there is a limitation to the intact physical representation such as influence of optical ambient light and brightness. In this paper, the display technology using physical deformation different from the existing optical display is approached as a cultural and emotional perspective. The purpose of this paper is to develop the multivariate display technology that can create 3D realistic stereoscopic images through projecting dynamic images on physically diversified screen by overcoming the limitations of 2D planar digital signage and study how to apply them to video, exhibition and performance.