• 반도체디스플레이기술학회지
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• 제22권3호
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• pp.149-154
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• 2023

This paper presents a novel approach to multi-focus image fusion using light field cameras. The proposed neural network, LFFCNN (Light Field Focus Convolutional Neural Network), is composed of three main modules: feature extraction, feature fusion, and feature reconstruction. Specifically, the feature extraction module incorporates SPP (Spatial Pyramid Pooling) to effectively handle images of various scales. Experimental results demonstrate that the proposed model not only effectively fuses a single All-in-Focus image from images with multi focus images but also offers more efficient and robust focus fusion compared to existing methods.

• 전자공학회지
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• 제39권10호
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• pp.71-77
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• 2012

• 천문학회보
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• 제30권1호
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• pp.56.2-56.2
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• 2005

• 대한원격탐사학회지
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• 제28권6호
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• pp.693-704
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• 2012

Space-born remote sensing camera systems tend to be developed to have very high performances. They are developed to provide extremely small ground sample distance, wide swath width, and good MTF (Modulation Transfer Function) at the expense of big volume, massive weight, and big power consumption. Therefore, the camera system occupies relatively big portion of the satellite bus from the point of mass and volume. However, the camera systems for lunar exploration don't need to have such high performances. Instead, it should be versatile for various usages under various operating environments. It should be light and small and should consume small power. In order to be used for national program of lunar exploration, electro-optical versatile camera system, called MAEPLE (Multi-Application Electro-Optical Payload for Lunar Exploration), has been designed after the derivation of camera system requirements. A ground model of the camera system has been manufactured to identify and secure relevant key technologies. The ground model was mounted on an aircraft and checked if the basic design concept would be valid and versatile functions implemented on the camera system would worked properly. In this paper, results of design and functional test performed with the field campaigns and air-born imaging are introduced.

• 천문학회보
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• 제26권2호
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• pp.54.1-54.1
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• 2001

• 한국정밀공학회지
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• 제29권3호
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• pp.295-301
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• 2012

The method for spraying of liquids through an electrical field has become a printing method since it can make very small droplet. For electro-hydrodynamic jet printing to become a reliable jetting tool, the jetting performance should be characterized with respect to various jetting conditions. To optimize jetting conditions, the jetting behavior should be measured. In this study, we present a visualization techniques to measure jetting behavior from electro-hydrodynamic (EHD) inkjet head. Unlike most previous method, we use the CCD camera to measure the jetting behavior. For this purpose, LED light is synchronized with jetting signal and sequential image was obtained by adjusting the delay time of the LED light. Finally, merits and demerits of using CCD camera were discussed to measure jetting image from EHD inkjet head.

• 한국컴퓨터그래픽스학회논문지
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• 제29권3호
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• pp.13-19
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• 2023

카메라 센서의 한계로 인하여 촬영 장면에 따라 한 번의 촬영으로 모든 영역의 밝기가 적절하게 촬영되지 않는 경우가 존재한다. 이러한 센서의 한계는 하이 다이나믹 레인지 이미징 기술을 통해서 극복이 가능하다. 한 장면을 다양한 노출 설정으로 여러 번 촬영하는 브라케팅은 움직이는 피사체를 찍기에 적절하지 않으며 촬영 시간이 길다는 단점이 있다. 본 연구는 한 번의 촬영으로 서로 다른 노출의 이미지를 얻을 수 있는 소형 라이트필드 카메라를 제안한다. 라이트필드 카메라는 대표적으로 두 가지 형태가 있는데, 첫 번째는 여러 대의 카메라를 어레이로 배치한 라이트필드 카메라 시스템이며, 두 번째는 대물렌즈 뒤에 마이크로 렌즈 어레이를 배치한 카메라이다. 본 연구에서 제작된 초박형 라이트필드 카메라는 센서 위에 마이크로 렌즈어레이가 부착되어있는 형태의 카메라로 각 렌즈 조리개 크기를 다르게 설계하여 한 번의 촬영으로 다른 노출의 촬영 결과를 얻을 수 있게 설계되었다. 촬영된 단일 영상들을 전처리 하여 이미지 품질을 높인 이후, HDR 알고리즘을 통해 각 단일 이미지들보다 다이나믹 레인지가 넓은 이미지를 획득하도록 구현하였다. 또한 노출 시간을 기준으로 설계된 식을 수정하여 조리개값에 따라 다른 가중치를 둘 수 있도록 바꾸었고, 이를 통해 단 한 번의 촬영을 통한 HDR 이미징을 구현하였다.

• Current Optics and Photonics
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• 제6권4호
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• pp.420-429
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• 2022

In this paper, the details and design process of an optical system for space target detection cameras are introduced. The whole system is divided into three structures. The first structure is a short-focus visible light system for rough detection in a large field of view. The field of view is 2°, the effective focal length is 1,125 mm, and the F-number is 3.83. The second structure is a telephoto visible light system for precise detection in a small field of view. The field of view is 1°, the effective focal length is 2,300 mm, and the F-number is 7.67. The third structure is an infrared light detection system. The field of view is 2°, the effective focal length is 390 mm, and the F-number is 1.3. The visible long-focus narrow field of view and visible short-focus wide field of view are switched through a turning mirror. Design results show that the modulation transfer functions of the three structures of the system are close to the diffraction limit. It can further be seen that the short-focus wide-field-of-view distortion is controlled within 0.1%, the long-focus narrow-field-of-view distortion within 0.5%, and the infrared subsystem distortion within 0.2%. The imaging effect is good and the purpose of the design is achieved.

• 방송공학회논문지
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• 제24권7호
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• pp.1246-1258
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• 2019

Since light field (LF) image has huge data volume, it requires high-performance compression technique for efficient transmission and storage of its data. Camera users may like to represent parts of image at different levels of focus at their choice anytime. To address this refocusing functionality, in this paper, we first render a focal stack consisting of multi-focus images, then compress it instead of original LF data. The proposed method has advantage of minimizing the amount of LF data to realize the targeted refocusing applications. Our experiment results show that the proposed method outperforms the state-of-the-art for LF image compression method.

• 천문학회보
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• 제45권1호
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• pp.69.2-69.2
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• 2020

Korea Astronomy and Space Science Institute (KASI) is developing a coronagraph to measure the coronal electron density, temperature, and speed utilizing spectral change of the K-corona around 400 nm. However, near UV light is more affected by atmospheric effect on the ground than visible light. For the total solar eclipse on July 2 2019, KASI organized an expedition team to test the possibility of the similar measurement scheme in the visible light. The observation site was in Las Flores, San Juan, Argentina. We built an imaging spectrograph using micro lenslet array and grism, named Coronal Integral Field Spectrograph (CorIFS). In addition, images of white light corona, wide field background, and all sky were taken with various camera settings. We present the preliminary results of the expedition.