• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.22-29
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• 2006

This paper considers the lens distortions such as a fisheye distortion and a perspective distortion. While a fisheye lens has a wide field-of-view, it causes a large distortion to the images. Regardless of a fisheye lens or a rectilinear lens, a lens generates perspective distortion in a vertical direction when the lens views in an upward direction or downward direction. These distortions deform images differently from human visual functions. Therefore, this paper presents a method to correct the distortions, and whereby, the research in this paper enlarges choices of images to image processing algorithm that may select the distorted images and the corrected images depending on applications. An infinite polynomial model is employed in the fisheye radial distortion correction, and the vertical perspective distortion correction is done by using a vanishing point. The methods introduced in this paper are implemented on the images captured by a rear-view camera installed on a vehicle and showed their robustness of the correction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.201-207
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• 2015

The smartphone with camera can easily generate an image instead of a scanner. However the document image through a smartphone can have distortions related rotation or perspective. In this paper, we proposed a method to generate the document image in that distortions are reduced from the captured document image through a smartphone. For this, the original document image through a smartphone is preprocessed using the MSER-b technique to reduce the light effect. Then, the text area contour is extracted using the characteristics of the document image. Lastly, rotation or perspective distortions are reduced using the extracted text area contour. For experiments, the proposed method is compared two other products. Through experiments, we show that the distortions within the captured document image through smartphone can be effectively reduced.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.232-237
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• 2010

In this paper, a slit light laser range finding method using perspective warping calibration is proposed. This approach has an advantage to acquire relatively high accuracy, although the optical system is nonlinear. In the calibration, we detect the calibration points which are marked on the calibration panel and acquire the center position of the slit light laser in the image, which are used for computing the real positions of the slit light by using perspective warping. A calibration file is obtained by integrating the calibration data with the transition of the panel. The range data is acquired by interpolating the center position of the slit light laser to the calibration coordinates. Experimental results show that the proposed method provides the accuracy of 0.08mm error in depth range of 130mm with the low cost optical system.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.596-601
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• 2000

In a robot/vision system, the vision sensor, typically a CCD array sensor, is mounted on the robot hand. The problem of determining the relationship between the camera frame and the robot hand frame is refered to as the hand-eye calibration. In the literature, various methods have been suggested to calibrate camera and for sensor registration. Recently, one-step approach which combines camera calibration and sensor registration is suggested by Horaud & Dornaika. In this approach, camera extrinsic parameters are not need to be determined at all configurations of robot. In this paper, by modifying the camera model and including the lens distortion effect in the perspective transformation matrix, a new one-step approach is proposed in the hand-eye calibration.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.172-179
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• 2002

In a robot/vision system, the vision sensor, typically a CCD array sensor, is mounted on the robot hand. The problem of determining the relationship between the camera frame and the robot hand frame is refered to as the hand-eye calibration. In the literature, various methods have been suggested to calibrate camera and for sensor registration. Recently, one-step approach which combines camera calibration and sensor registration is suggested by Horaud & Dornaika. In this approach, camera extrinsic parameters are not need to be determined at all configurations of robot. In this paper, by modifying the camera model and including the lens distortion effect in the perspective transformation matrix, a new one-step approach is proposed in the hand-eye calibration.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.132-132
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• 2019

첨단 IT기술과 음파와 영상을 이용한 하천 계측 기술의 결합을 통해 하천 수위와 유속을 자동으로 측정하는 기술들이 개발되고 있다. 특히, 표면영상을 이용한 자동유량계측 기술은 카메라 외에 별도로 고가의 장비를 구입할 필요가 없을 뿐 아니라 현장 상황을 영상으로 확인할 수 있기 때문에 현장조사 인력이 필요가 없어 경제적이고, 비접촉식으로 안전하여 각광받고 있는 기법이다. 하지만 표면영상유속계는 기본적으로 원근에 따른 영상왜곡이 발생하기 때문에 이를 정사영상으로 변환하는 과정이 반드시 필요하다. 하지만 대하천과 같이 하폭이 넓은 경우에는 참조점을 이용한 영상왜곡 보정이 어렵다는 한계가 있다. 또한 참조점을 이용한 영상왜곡 변환 방법의 경우 수위변화가 있는 경우 대응이 어렵다는 한계가 있다. 이에 본 연구에서는 참조점을 이용한 영상왜곡 보정 작업이 필요 없는 지표영상유속측정법(IIVM, Index Image Velocimeter)을 개발하였다. 지표영상유속측정법은 기존 표면영상유속계 달리 복잡한 영상좌표변환 과정을 매우 간단하게 처리할 수 있는 장점이 있다. 지표영상유속측정법은 지표영상유속과 카메라와 수표면 사이의 거리를 고려한 지표유속을 사용하고, 이를 통해 기존 표면영상유속계의 한계인 수위변화를 고려하기 어려웠던 점을 극복할 수 있었다. 본 연구에서는 수리실험과 현장영상을 활용하여 수위 변화에 따른 지표유속을 측정한 결과 하천 수위가 변화하는 상황에서도 표면유속을 정확하게 산정할 수 있었고, 실제 측정유속을 대신할 수 있는 지표유속으로도 활용 가능한 것을 확인하였다.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.4
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• pp.41-52
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• 2014

In this paper, O-ring size measurement algorithm based on a small machine vision inspection equipment which can replace a expensive and large machine vision inspection equipment is presented. The small machine vision inspection equipment acquires a image from a CCD camera shooting a measurement plane which located on a back light and the proposed size measurement algorithm is apply to the image. For improvement of size measurement accuracy, camera lens distortion correction and perspective distortion correction are conducted by software technique. Consider O-ring's shape, ellipse fitting model is applied. In order to increase the reliability of ellipse fitting, RANSAC algorithm is applied.

• Journal of Korea Multimedia Society
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• v.15 no.6
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• pp.784-793
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• 2012

Defects of TFT-LCD is detected by thresholding the difference image between the input image and template one because LCD panel has its inherent patterns. However, the pitch corresponding to pattern period is gradually changed according to the distance from the center of camera due to geometric distortion of camera characteristics. This paper presents a method to detect defects through comparing the pitch area with neighbor pitch areas where the perspective transform is performed with the extracted features to correct the distortion. The experimental results show that the performance of the proposed method is very effective for real data.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.28-29
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• 2012

IT 및 자동차 관련 기술의 융합 기술의 발전에 따라 자동차의 안전 및 운전편의 정보 제공에 대한 관심이 높아지면서 인간의 시각 및 지각의 한계를 보완해 줄 수 있는 보조 도구들에 대한 연구 및 개발이 활발히 이루어지고 있다. 그러나 기존의 컴퓨터 비전 기반 도로 교통 표지판 자동 검출 및 인식 기술들은 센싱 장비들의 가격 또는 조도와 원근감에 따른 교통 표지판의 색상과 모양 왜곡으로 인해 해당 표지판들의 검출을 어렵게 한다. 따라서 본 논문에서는 차량 내 탑재가 가능한 저가의 비전 카메라를 이용하여 교통표지판 칼라 분석 및 원근 보정을 통해 운전자에게 효과적으로 도로표지판 정보를 제공할 수 있는 검출기법을 제안한다. 실험을 통해 도로주행영상 내 도로표지판들을 효과적으로 검출할 수 있음을 확인하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.292-295
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• 2012

본 연구는 촬영을 통해 얻어진 투사면을 이용하여 투사면과 프로젝터 사이의 거리를 측정하고, 이미지 내에서 투사면이 가질 수 있는 영상의 원근 왜곡을 보정하는 프로젝션 맵핑에 대한 영상처리 기술을 제안한다. 그리하여, 결과적으로 프로젝터의 초기 설치에 소요되는 시간을 줄이고 변화된 투사면에 적합하게 프로젝션 맵핑이 이뤄짐에 따라 프로젝션 맵핑의 완성도를 높이고자 한다.