• 방송공학회논문지
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• 제9권3호
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• pp.246-256
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• 2004

본 논문에서는 새로운 무손실 영상 압축 알고리즘을 제안한다. 무손실 영상 압축(Lossless Image Compression)은 Prepress Industry, Remote Sensing, Image archival system과 같이 정확성과 정밀도를 요하는 분야에서 사용된다 무손실 영상 압축은 원 영상와 복원 영상가 완전히 일치하여 품질을 그대로 유지할 수 있으나. 압축 효율 면에서는 만족할 만한 효과를 볼 수 없다. 기존의 대표적인 무손실 영상 압축 방법으로는 CALIC과 JPEG-LS이 있다. CALIC은 높은 압축률을 나타내지만, 3-PASS의 선처리과정을 요구하여 복잡도가 높아지는 단점이 있는 반면 JPEG-LS는 압축률에서 CALIC에 못 미치지만 복잡도가 낮아 부호화/복호화 과정이 빠르며 이 분야의 표준으로 지정되어 있다. 본 논문에서 제안한 영창 적응형 무손실 영상 압축기술은 다수의 예측기를 통해 현재 화소에 가장 적절한 오차값을 예측하였다. 또한, 산술 부호화(arithmetic coding)시 다수의 심볼 확률 모델을 사용함으로써, 단일 모델을 이용하는 방식에 비해 압축 효율을 향상시켰다. 다중 모델을 이용하는 방식은 본 논문에서 제안한 방식뿐만 아니라, 다른 무손실 영상 압축방법에도 그대로 적용이 가능하다. 실험 결과, JPEG-LS보다 약 5％의 압축 효율 향상이 있었다. 또한 CALIC과는 압축효율이 같거나 근소한 우위를 나타냈다.

• 복식
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• 제59권4호
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• pp.67-81
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• 2009

This study aims to characterize the effect of different combinations of chromatic-achromatic colors and 1:2:3 area-ratio variation of stripe necktie, and gender on the image of male wearer. The experimental materials developed for this study are a set of stimuli and response scales. The stimuli consist of 84 color pictures manipulated with every combination of 12 different colors and 7 different area-ratio. The 7-point scale designed for visual evaluation of image formation included 26 bipolar adjectives. The subjects were 2016 undergraduate students in Gyeongnam, Seoul, Busan, and Daegu areas. The results of this study were as follows. The analyses of images of male wearer in terms of combinations of chromatic-achromatic colors and I :2:3 area-ratio variation of oblique stripe necktie reveal that the concerned factors are of five characteristic dimensions of youth-activity, ability, attractiveness, appeal, and warmness. In addition, it has been found that individual images of male wearer are affected by observer's gender as well as combinations of chromatic-achromatic colors and 1:2:3 area-ratio variation of stripe neckties and that those images vary with every combination of each factor. The study results are highly expected to be used as useful sources in developing necktie designs.

• 치과방사선
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• 제16권1호
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• pp.59-68
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• 1986

The purpose of this investigation was to locate the central plane of the image layer on the panoramic machine relative to a specific point on the machine. In the study of the central plane of the image layer of panoramic radiograph, using the Morrita Company PANEX-EC a series of 33 exposures were taken with the 4-5 experimental pins placed in the holes of the plastic model plate, then evaluated by human eye. The author analyzed the central plane of the image layer by Mitutoyo-A-221 and calculated horizontal and vertical magnification ratio in the central plane of the image layer determined experimentally. The results were as follows: 1. The location of the central plane of the image layer determined experimentally was to lateral, compared with manufactural central plane. 2. Horizontal magnification ratio in the central plane of the image layer determined experimentally was 9.25%. 3. Vertical magnification ratio in the central plane of the image layer determined experimentally was 9.17%.

• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1737-1744
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• 2004

In the compression methods widely used today, the image compression by VQ is the most popular and shows a good data compression ratio. Almost all the methods by VQ use the LBG algorithm that reads the entire image several times and moves code vectors into optimal position in each step. This complexity of algorithm requires considerable amount of time to execute. To overcome this time consuming constraint, we propose an enhanced self-organizing neural network for color images. VQ is an image coding technique that shows high data compression ratio. In this study, we improved the competitive learning method by employing three methods for the generation of codebook. The results demonstrated that compression ratio by the proposed method was improved to a greater degree compared to the SOM in neural networks.

• 전자공학회논문지
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• 제50권12호
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• pp.247-253
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• 2013

본 연구의 목적은 Direct DR(Digital Radiography), Indirect DR, I.I(Image Intensifier) DR에서 X선 광자 검출 방식에 따른 선량측정 및 획득된 영상을 정량적이고 객관적인 측정을 통해 DR System을 비교 평가 하는 것이다. Rando phantom을 사용하여 입사표면선량을 측정하였으며, 측정된 입사표면선량 값을 통해 PCXMC 프로그램을 사용하여 유효선량과 방사선 조사로 인한 위험을 평가하였다. 21cm 아크릴 phantom을 사용하여 SNR(Signal to Noise Ratio), NPS(Noise Power Spectrum), CNR(Contrast to Noise Ratio)을 측정하였으며, 측정값은 통계학적 분석기법을 사용하여 유의성을 평가하였다. 입사표면선량, 주요장기선량, 유효선량 모두 direct DR이 가장 낮게 측정되었으며, direct DR 선량을 기준으로 I.I type DR은 약 1.3배, indirect DR은 약 2.4배 높은 선량 비율로 측정되었다. 방사선량에 따른 위험도 역시 동일한 비율로 측정되었다. SNR 측정 결과 direct DR측정값을 기준으로 I.I DR은 약 7.25배, indirect DR이 약 1.48배 낮은 비율로 측정되었다. CNR 측정 결과 direct DR 측정값을 기준으로 I.I DR은 약 1.16배 높고, indirect DR이 약 0.87배 낮은 비율로 측정되었다. 따라서 a-selenium 검출소자를 사용하여 X선 광자를 검출하는 방식인 direct DR은 적은 선량으로 우수한 화질의 영상을 구현함으로써 선량에 민감한 소아나 생식선이 포함된 검사 등에 유용할 것으로 사료된다. 또한 많은 진단 정보를 위한 영상 평가가 요구되는 경우에는 indirect DR이 유용할 것으로 판단된다.

• Journal of Multimedia Information System
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• 제8권2호
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• pp.93-100
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• 2021

Under the time-varying temperature, the high-temperature radiation of forgings and the change of reflection characteristics of oxide skin on the surface of forgings lead to the difficulty of obtaining images to truly reflect the geometric characteristics of forgings. It is urgent to study the clear and reliable acquisition method of hot forging feature image under time-varying temperature to meet the requirements of visual measurement of hot geometric parameters of forgings. Based on this, this chapter first puts forward the quality evaluation method of forging feature image, which provides guarantee for the accurate evaluation of feature image quality. Furthermore, the factors that affect the image quality, such as the radiation characteristics of forgings and the photographic characteristics of cameras, are analyzed, and the imaging spectrum which can effectively suppress the radiation intensity of forgings is determined. Finally, aiming at the problem that the quality of image acquisition is difficult to guarantee due to the drastic change of radiation intensity of forgings under time-varying temperature, an image acquisition method based on minimum signal-to-noise ratio (SNR) based laser light intensity adaptation is proposed, which significantly improves the definition of feature light strips in forging images at high temperature, and finally realizes the clear acquisition of feature images of large-scale hot forging under time-varying temperature.

• 펄프종이기술
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• 제34권3호
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• pp.25-31
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• 2002

The purpose of this study was to analyze how the fiber properties and mixing ratio of softwood and hardwood pulp affect on roundness of printed image. Softwood pulp and hardwood pulp were refined to 400 and 600ml CSF by Valley beater and handsheets of 70 g/$m^2$ basis weight were made at different mixing ratios of hardwood and softwood pulp. The roundness, dot area, and shape of the printed dot were measured by Image Analyzer. The depths and shapes of the acridine orange penetration into paper were measured by CLSM. With higher mixing ratio of hardwood pulp, the paper showed higher air-permeability and better formation, especially at lower freeness. The roundness of the printed image became better and the dot size became smaller when the amount of hardwood pulp increased. Penetration depth of acridine orange by CLSM became greater and roundness increased to real circle when the amount of hardwood pulp increased. It was thought that higher mixing ratio of hardwood fibers resulted in efficient penetration by better formation with uniform micro-pore distribution and it increased roundness. It was thought that fiber properties and mixing ratio affected the structure of paper and the shape of the printed dot. This study showed that the measurement of depth of the liquid penetration into paper without destruction and contact was feasible. Moreover, this method showed that the shape of the liquid penetration was measurable.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.202-207
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• 2002

EOC (Electro-Optical Camera) of KOMPSAT-1 (Korea Multi-Purpose SATellite) has been producing land imageries of the world since January 2000. After image data are acquired by EOC, they are transmitted from satellite to ground via X-band RF signal. Then, EOC image data are generated and pass through radiometric and geometric corrections to generate standard products of EOC images. After radiometric correction on EOC image data, Modulation Transfer Function (MTF) compensation is applicable on EOC images with user's request for better image quality. MTF compensation is concerned with filtering EOC images to minimize the effect of degradations. For Image Receiving and Processing System (IRPE) at KOMPSAT Ground Station (KGS), Wiener filter is used in MTF compensation for EOC images. If the Pointing Spread Function (PSF) of EOC system is known, signal-to-noise power spectra ratio is the only factor in the determination of Wiener filter. In this paper, MTF compensation in IRPE at KGS is introduced and MTF compensated EOC 1R images are generated using Wiener filters with various signal-to-noise power spectra ratios. MTF compensated EOC 1R images are correlated with EOC 1R images for observing linearities between them. As a result, the effect of signal-to-noise power spectra ratio is shown on MTF compensated EOC 1R images.

• 대한원격탐사학회지
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• 제19권1호
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• pp.43-52
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• 2003

EOC (Electro-Optical Camera) of KOMPSAT-1 (Korea Multi-Purpose SATellite) has been producing land imageries of the world since January 2000. After image data are acquired by EOC, they are transmitted from satellite to ground via X-band RF signal. Then, EOC image data are retrieved and pass through radiometric and geometric corrections to generate standard products of EOC images. After radiometric correction on EOC image data, Modulation Transfer Function (MTF) compensation is applicable on EOC images with user's request for better image quality. MTF compensation is concerned with filtering EOC images to minimize the effect of degradations. For Image Receiving and Processing System (IRPE) at KOMPSAT Ground Station (KGS), Wiener filter is used for MTF compensation of EOC images. If the Pointing Spread Function (PSF) of EOC system is known, signal-to-noise (SNR) power spectra ratio is the only variable which determines the shape of Wiener filter In this paper, MTF compensation in IRPE at KGS is briefly addressed, and MTF compensated EOC images are generated using Wiener filters with various SNR power spectra ratios. MTF compensated EOC images are compared with original EOC 1R images to observe correlations between them. As a result, the effect of SNR power spectra ratio on MTF compensated EOC images is shown.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.1869-1876
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• 2009

기존 종이 문서를 영상 파일로 변환하기 위해서 스캐너와 같은 광학기를 사용하게 된다. 스캐닝 과정에서 문서가 제대로 문서 영상으로 생성되었는지를 판단하기 위해서 이미지 품질 검사 과정을 거치게 된다. 이미지 품질검사 과정에서는 스캐너 기기의 특성상 스캐닝 과정에서 발생할 수 있는 문서 영상의 기울기, 노이즈 여부, 문서가 접힌 상태로 스캔되었는지의 여부 등을 체크하게 된다. 이에 본 논문에서는 스캐너를 이용하여 문서 영상을 생성 과정에서 발생하는 기하학적 변형을 평가하기 위한 방법론을 제시한다. 본 연구에서는 품질 검사의 검사 항목에 대해서 영상 처리를 이용하여 각각의 변형 정도를 측정하고 각각의 변형 정도가 실제 문서의 가독성에 얼마나 영향을 미치는지를 OCR 결과 값과 비교한다. OCR 인식 성공 비율과 각 항목별 변형 정도를 나타내는 측정 값 간에 상관관계를 분석하기 위해서 피어슨 상관 계수(Pearson Correlation Coefficient)를 이용하고 이를 기반으로 실제 문서 영상의 변형정도를 평가하기 위한 가중치 값을 산정한다. 제시한 방법으로 평가에서 높은 평가 값으로 계산된 영상 문서는 OCR 인식률에서도 높은 인식 결과를 나타내고 있다.