• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.189-193
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• 1997

Aspheric pick-up lenses are increasingly used in consumer products such as computer and multimedia, as their mass production has become possible owing to the injection molding process. However still much work needs to be done for more effective manufacture of aspheric lenses, one area of which is the in-line inspection of produced lenses. In this paper, we present a lateral-shearing interferometer that has specially been designed to have a high immunity to external vibration and atmospheric disturbance. The interferometer comprises four prisms. They are directly attached to each other using an immersion oil so that relative sliding motions between the prisms are allowed. Their relative displacement can readily generate necessary lateral-shearing and phase-shifting to determine the wavefront of the beam collimated by the lens under inspection. A special phase-measuring algorithm of arbitrary-bucket is adopted to compensate the phase-shifting error caused by the thickness reduction in the immersion oil. Zernike polynomial fitting has done for determinating quantitative aberration of aspheric pick-up lenses. The interferometer built in this work is robust to external mechanical vibration and atmospheric disturbance so that experimental results show that it has a repeatability of less than λ/100.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2301-2306
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• 2011

Current general-purpose electromagnetic field simulators have been widespread applied, and is being used to electromagnetic problems such as antenna design, EMC design, measurement, and microwave device design, etc. This paper is to solve various electromagnetic problems in X-band region for utilizing multi-core-based PC available network resources more efficiently. The electromagnetic field simulator based on TCP / IP-based network topology, configuration, and its framework design is proposed and its availability is examined.

• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.21-28
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• 2014

In this paper a Super Multi-view display method using a pinhole array with full parallax was proposed. The proposed method was simulated and its parameters analyzed. Also, the distribution and irradiance of light through each pinhole on the retina receiver, according to the change of crystalline lens focal length, were found by simulation. As a result, an image free of blurring was obtained while the crystalline lens focused on the depth plane of the three-dimensional image created by the imaging lens.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.137-140
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• 2000

카메라의 렌즈 등 광학장비의 성능 제한으로 인하여 초점이 맞지 않아 흐려지고 잡음으로 훼손된 영상을 복원하는데 일반적으로 반복복원방법이 사용된다. 이 경우에 가속변수는 훼손영상에 관계없이 영상전체에 일률적으로 적용되기 때문에 흐려짐 훼손이 심한 윤곽부분도 훼손이 작은 평면영역이 같이 일정하게 처리되어 수렴속도가 느려지고 시각적으로 중요한 윤곽부분의 복원에는 효율적이지 못하다. 이러한 문제점을 해결하기 위하여 본 논문에서는 흐려짐 훼손이 작은 평면영역은 가속변수를 작게하고 훼손이 큰 윤곽영역은 가속변수를 크게 하여 영상의 국부적인 특성에 따라 적응적으로 반복 복원하는 방법을 제안하였다. 제안한 복원방법은 기존의 방법과 비교하여 수렴속도가 빨라지고 시각적으로 중요한 윤곽정보의 복원에도 효율적임을 실험결과를 통해 할 수 있었으며, MSE면에서도 우수하였다.

• Journal of Korea Multimedia Society
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• v.22 no.2
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• pp.128-135
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• 2019

This paper presents a deep learning-based object detection method for recognizing vehicles in images acquired through cameras installed on ceiling of underground parking lot. First, we present an image enhancement method, which improves vehicle detection performance under dark lighting environment. Second, we present a new CNN-based multiscale classifiers for detecting vehicles in images acquired through cameras with fisheye lens. Experiments show that the presented vehicle detector has better performance than the conventional ones.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.2
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• pp.137-148
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• 2004

In this paper, we propose a new camera calibration method for rotating multi-view cameras to generate image-based panoramic 3D Virtual Environment. Since calibration accuracy worsens with an increase in distance between camera and calibration pattern, conventional camera calibration algorithms are not proper for panoramic 3D VE generation. To remedy the problem, a geometric relationship among all lenses of a multi-view camera is used for intra-camera calibration. Another geometric relationship among multiple cameras is used for inter-camera calibration. First camera parameters for all lenses of each multi-view camera we obtained by applying Tsai's algorithm. In intra-camera calibration, the extrinsic parameters are compensated by iteratively reducing discrepancy between estimated and actual distances. Estimated distances are calculated using extrinsic parameters for every lens. Inter-camera calibration arranges multiple cameras in a geometric relationship. It exploits Iterative Closet Point (ICP) algorithm using back-projected 3D point clouds. Finally, by repeatedly applying intra/inter-camera calibration to all lenses of rotating multi-view cameras, we can obtain improved extrinsic parameters at every rotated position for a middle-range distance. Consequently, the proposed method can be applied to stitching of 3D point cloud for panoramic 3D VE generation. Moreover, it may be adopted in various 3D AR applications.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.231-236
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• 2013

We investigated the optical design of a smart headlamp capable of producing various beam patterns through only on/off modulation of light sources. This was implemented by forming a continuous matrix of beams from discontinuous beam patterns by means of a multi-array LED optical system. As one such optical system, the multi-array LED system is a convenient and economical device for implementing beam patterns with the simple on/off modulation of the light sources. A single optical assembly module can be made by combining a multiple-LED array, optical system module, and electronic control with no need for any additional mechanical components. The present optical system was designed to include a secondary lens and a projection lens mounted at the front of each LED in the array to realize accurate lighting patterns as well as the required luminosity at a distance of 25 m in the forward direction. Finally, we identified and analyzed the patterns implemented by the designed optical system that produced satisfactory performance of high beams and adaptive driving beams (ADB).

• Journal of Digital Contents Society
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• v.16 no.2
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• pp.227-234
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• 2015

Recently, there is more and more demand on broadcasting display environment that provides a sense of realism basically with high quality and high definition as in UHDTV, so various kinds of 4K cameras have been released. Super 35mm sensor 4K/UHD cameras being generally used can be usefully applied to the single camera-based system such as advertisements, dramas, nature documentaries, and culture programs. However, in the multicamera-based system such as entertaining programs, sports, and concerts, relay broadcasting may face limitations as there are restrictions of close-up or tight shots according to the distance. Besides, 4K lenses are not enough compared with the previous HD lenses' group, so there are limitations in camera photographing shots that have been realized in HD filming. Therefore, to complement this, the use of 2/3 inch sensor 4K/UHD cameras is being demanded, and it is also needed to use various lenses' groups to produce UHD image contents. Accordingly, this study used Grass Valley's LDX 4K/UHD camera to analyze its applicability based on the picture quality test at the use of HD lenses in 2/3 sensors and also the possibility of its efficient application.

• Journal of Korea Multimedia Society
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• v.17 no.2
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• pp.257-265
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• 2014

3 dimensional stereoscopic is attracting new attention as it simulates human eye and related hardware advances. However, 3 dimensional stereoscopic requires more time and effort than 2D movie because it uses 2 cameras or 2 lenses. This study analyzed the merits and demerits of the system producing rider movie using 3 dimensional stereoscopic shooting techniques and searched a way to produce better 3 dimensional stereoscopic rider movie which meets the producing intention by applying elements required to create effective 3 dimensional stereoscopic effect. According to the study result, a light-weight integrated system was effective to create 3 dimensional stereoscopic rider movie because of its genre characteristic. In the post-production of the work, location shooting considered of time re-mapping, color correction and graphic element addition was required.

• Journal of Korea Multimedia Society
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• v.23 no.3
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• pp.395-401
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• 2020

In this paper, a motion-based ROI extraction algorithm from a high resolution fisheye image is proposed for multi-view monitoring systems. Lately fisheye cameras are widely used because of the wide angle-of-view and they basically provide a lens correction functionality as well as various viewing modes. However, since the distortion-free angle of conventional algorithms is quite narrow due to the severe distortion ratio, there are lots of unintentional dead areas and they require much computation time in finding undistorted coordinates. Thus, the proposed algorithm adopts an image decimation and a motion detection methods, that can extract the undistorted ROI image with a standard angle-of-view for the fast and intelligent surveillance system. In addition, a mesh-type ROI is presented to reduce the lens correction time, so that this independent ROI scheme can parallelize and maximize the processor's utilization.