• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.227-230
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• 2002

A digital watermark is an invisible mark embedded in a digital image which used for copyright protection. In this paper, we propose a new optical watermarking system. A optical watermarking system is applied for digital watermarking by phase hologram and Mach-Zehnder interferometer. A optical watermarking technique to be hidden is phase modulated in a random patten, and its Fourier-transformed hologram image is superposed on a content image. The autentication information extract by using Mach-zehnder interferometer.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.827-833
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• 2012

본 논문은 2D/3D 변환에서 깊이정보 생성을 위해 연산량을 감소시키는 레벨 간소화 기법을 적용하고 객체의 고유벡터를 이용하여 노이즈를 제거한 Optical flow를 이용하는 방법을 제안한다. Optical flow는 깊이정보를 생성하기 위한 방법 중 하나로 두 프레임간의 픽셀의 변화 벡터 값을 나타내어 움직임 정보를 나타내며 픽셀 단위로 처리하므로 정확도가 높다. 그러나 픽셀 단위 연산으로 긴 연산 시간이 소요되며 모든 픽셀을 연산하는 특성상 노이즈가 생길 수 있는 문제점이 있다. 본 논문에서는 이를 해결하기 위해 레벨 간소화 과정을 거쳐 연산 시간을 단축하였고 Optical flow를 영상에서 고유벡터를 갖는 영역에만 적용하여 노이즈를 제거한 뒤 배경 영역에 대한 깊이 정보를 에지 영상을 이용하여 생성하는 방법을 제안하였다. 제안한 방법으로 깊이정보를 생성한 뒤 DIBR(Depth Image Based Rendering)으로 2차원 영상을 3차원 입체 영상으로 변환하였고 SSIM(Structural SIMilarity index)으로 최종 생성된 영상의 오차율을 분석하였다.

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.136-146
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• 2008

We proposed an adaptive steganography of an optical image using bit-planes and multichannel characteristics. The experiment's purpose was to compare the most popular methods used in optical steganography and to examine their advantages and disadvantages. In this paper we describe two digital methods: the first uses less significant bits(LSB) to encode hidden data, and in the other all blocks of $n{\times}n$ pixels are coded by using DCT(Digital Cosine Transformation), and two optical methods: double phase encoding and digital hologram watermarking with double binary phase encoding by using IFTA(Iterative Fourier Transform Algorithm) with phase quantization. Therefore, we investigated the complexity on bit plane and data, similarity insert information into bit planes. As a result, the proposed method increased the insertion capacity and improved the optical image quality as compared to fixing threshold and variable length method.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.110-140
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• 1998

One of the problems facing in all modern dental hospitals is the much efforts, manpower and space are needed to effectively sort and stack patients' charts of the various dental departments. In addition, the storage and prompt arrangement of x-ray films is also a problem. Therefore, if dental charts as well as films could be computerized, it would be easier to store and keep them; by data basing, many space, manpower and cost would be saved: data could also be effectively managed for the purpose of academic researches. This would be an epoch -making event in the development of dental hospital management. The purpose of this study is to develop a dental information processing program, that will be used to store dental treatment records and digital image data using a new record media, the optical card. The patients' charts from the dental hospital were selected. The treatment records of the chart were put into the treatment data -recording area of the program, and the digital images of various dental x-ray films were made with a scanner. These data were stored in the optical card and analyzed to get the following results: 1. In this program it is possible to put treatment records and image data into and out from the optical card, and it is impossible to correct and delete all data recorded on the optical card. 2. All data in the optical card system can be searched and analyzed on database. 3. The resolution of image data stored in optical card is above 5.9 lp/mm. 4, All data of dental charts used as samples, stored to optical cards, occupies average 14%, In conclusion, with the development of the storage system using the optical card, a dental patient's life-time treatment record can be stored in one optical card and used as a substitute for the dental chart.

• 반도체디스플레이기술학회지
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• 제7권1호
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• pp.11-16
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• 2008

Confocal scanning microscopy is a widely used technique for three dimensional measurements because it is characterized by high resolution, high SNR and depth discrimination. Generally an image is generated by moving one optical probe that satisfies the confocal condition on the specimen. Measurement speed is limited by movement speed of the optical probe; scanning speed. To improve measurement speed we increase the number of optical probes. Specimen region to scan is divided by optical probes. Multi-point information each optical probe points to can be obtained simultaneously. Therefore image acquisition speed is increased in proportion to the number of optical probes. And multiple optical probes from red, green and blue laser sources can be used for color imaging and image quality, i.e., contrast, is improved by adding color information by this way. To conclude, this technique contributes to the improvement of measurement speed and image quality.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.62-63
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• 2003

We propose an improved image encryption and the shift-tolerance method in the Fourier space using a virtual phase image. The encrypted image is obtained by the Fourier transform of the product of a phase-encoded virtual image, not an original image, and a random phase image. We demonstrate the robustness to noise, to data loss and shift of the encrypted image or the Fourier decryption key in the proposed technique.

• Current Optics and Photonics
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• 제4권4호
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• pp.336-344
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• 2020

Exact optical characterization of virtual and augmented reality devices using conventional luminance measuring methods is a time-consuming process. A new measurement method is proposed to estimate in a relatively short time the boundary of ray trajectories emitting from a specific position on a virtual images. It is assumed that the virtual image can be modeled to be formed in front of one's eyes and seen through some optical aperture (field stop) that limits the field of view. Circular and rectangular shaped virtual images were investigated. From the estimated ray boundary, optical characteristics, such as the viewing direction and three dimensional range inside which a eye can observe the specified positions of the virtual image, were derived. The proposed method can provide useful data for avoiding the unnecessary measurements required for the previously reported method. Therefore, this method can be complementary to the previously reported method for reducing the whole measurement time of optical characteristics.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.82-87
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• 1998

Laser printer, faximile and copy machine are a few examples of OA(office automation) system. In such a system, the reflecting mirror has been employed for transmitting a target image to optical device. Therefore, to develope a good quality of optical system, the quality control of optical mirror was required. In recent years, considerable efforts have been directed toward the development of automated optical glass inspection system because the inspection is eye-fatigue and monotonous job for humans to perform. In this paper, we propose a inspection system applying algorithm of image processing for detecting defects of optical glass such as pinhole, scratch. From the experiments, the proposed inspection system shows reliable results.

• 한국광학회지
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• 제23권3호
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• pp.97-102
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• 2012

일반적으로 왜곡을 측정하는 방법으로 패턴의 전체 이미지를 분석하여 왜곡을 평가하는 방법을 이용하고 있으나 정확도가 높지 않아 카메라 등의 광학계에 많이 적용되고 있다. 1um이하의 정확도를 요구하는 왜곡수차를 측정하는 방법으로는 고가의 정밀 스테이지를 이용하여 마스크의 이미지 위치를 정확히 측정하는 방법이 주로 이용된다. 본 논문에서는 정확도가 요구되지 않는 매뉴얼 스테이지를 이용하여 왜곡을 정확히 측정하는 방법을 연구 하였다. 주요 아이디어로는 CCD나 CMOS를 이용하여 마스크 이미지를 일부 중첩되도록 분할측정하고 인접중첩영역의 이미지를 통합하여 마스크 이미지 위치를 정확히 계산하는 것이다. 마스크 이미지의 정확한 위치정보를 얻기 위해 Canny Edge Detection 기법을 사용하였으며 이렇게 확보된 위치정보로부터 좌표변환과 최소자승법을 사용하여 정확한 왜곡수차를 계산하는 과정을 연구하였다.

• 한국위성정보통신학회논문지
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• 제9권3호
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• pp.47-52
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• 2014

본 논문은 이미지 처리 기술을 이용한 광 카메라 통신(OCC: Optical Camera Communications) 기술을 제안한다. OCC 시스템의 구조 및 동작을 제안한다. 상용 30fps 카메라의 샘플링 동작에 의해 제한되는 데이터율을 증가시키기 위해 칼라 이미지 처리기술을 이용한 멀티칼러 전송기법을 제안한다. 멀티칼라 부호화 및 이미지 처리기반의 복호화 기법을 제안한다.