• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.714-717
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• 2018

This paper presents a method of HDR imaging with adaptive saturation compensation for brightness change. The saturation of HDR images were lighten on dark region because conventional HDR methods have focused on brightness change. Therefore, the proposed HDR method compensates saturation adaptively according to brightness change. For experiments of several images, the proposed algorithm is superior to conventional HDR methods qualitatively and quantitatively in terms of color saturation.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.550-553
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• 2010

최근 영화, 광고 그리고 증강현실과 혼합현실 등 다양한 분야에서 실제 영상에 가상의 객체를 합성하는 기법이 자주 사용되고 있다. 보다 사실적인 합성 결과를 생성하기 위해서는 실제 배경영상의 광원정보를 그대로 적용해야 한다. 이러한 실 세계의 광원 정보를 이용하기 위해서는 HDR(High Dynamic Range) 영상을 생성해야 한다. 일반적으로 HDR 영상을 생성하기 위해서는 고가의 HDR 카메라를 사용하거나 LDR(Low Dynamic Range) 카메라를 사용하여 노출 시간을 달리한 일련의 LDR 영상을 촬영하여 이를 기반으로 HDR 영상을 생성해야 한다. 본 논문에서는 이러한 단점을 보완하기 위해 한 장의 LDR 환경 맵을 HDR 환경 맵으로 복원하는 방법에 대해 제안한다. 제안하는 방법을 통해 LDR 환경 맵을 HDR 환경 맵으로 복원할 수 있으며 결과에서 볼 수 있듯이 HDR 영상을 이용했을 때와 유사한 렌더링 결과를 생성할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.705-708
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• 2015

High dynamic range (HDR) imaging is a techniques used in imaging to reproduce a greater dynamic range of luminosity than is possible with standard digital imaging. Tone mapping of HDR images for realistic display is commonly studied. However, scientific visualization of HDR image for analysis of scene luminance has much less attention. In this paper, we present and implement a simple approach for the reproduction and visualization of color information in HDR images. We attempt several simple color visualizing functions, and estimate their effectiveness through the evaluation factors with common HDR images.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.82-86
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• 2017

High dynamic range (HDR) imaging offers a radically approach of representing colors in digital images. Instead of using the range of colors produced by given devices, HDR imaging method manipulates and stores all colors and brightness levels visible to the human eye. To faithfully represent, store and then reproduce all these effects, the original scene must be stored and treated using high fidelity HDR techniques. Then, tone mapping is required to accommodate HDR image to low dynamic range (LDR) devices, and tone mapping operation of HDR image for realistic display is commonly researched. However, color visualization for analyzing scene luminance in HDR imaging has less attention from researches. This paper presents and implements a method for reproduction and visualization of the false color in HDR images. We produce a color visualization framework with several mapping functions, and evaluate their effectiveness by using RMAE and SNR with commonly used HDR image data. Experiment reveals that the sigmodal mapping function shows better performance in the false color visualization, compared to other methods.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.2
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• pp.10-20
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• 2008

Generally, to acquire an HDR image, many images that cover the entire dynamic range of the scene with different exposure times are required, then these images are fused into one HDR image. This paper proposes an efficient method for the HDR image acquisition with small number of images. First, we estimated scenic dynamic range using two images with different exposure times. These two images contain the upper and lower limit of the scenic dynamic range. Independently of the scene, according to varied exposure times, similar characteristics for both the maximum gray levels in images that include the upper limit and the minimum gray levels in images that include the lower limit are identified. After modeling these characteristics, the scenic dynamic range is estimated using the modeling results. This estimated scenic dynamic range is then used to select the proper exposure times for the acquisition of an HDR image. We selected only three proper exposure times because entire dynamic range of the cameras could be covered by three dynamic range of the cameras with different exposure times. To evaluate the error of the HDR image, experiments using virtual digital camera images were carried out. For several test images, the error of the HDR image using proposed method was comparable to that of the HDR image which utilize more than ten images for the HDR image acquisition.

• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1399-1408
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• 2012

The light source is an important visual component that empirically affects the color and illumination of graphic objects, and it is necessary to precisely store and appropriately employ the information of all light sources in the real world in order to obtain photo-realistic composition results. The information of real light sources can be accurately stored in HDR environment maps; however, it is impossible to create new environment maps corresponding to dynamic virtual light sources from a single HDR environment map captured under a fixed lighting situation. In this paper, we present a technique to dynamically generate well-matched information for arbitrarily selected virtual light sources using HDR environment maps created under predefined lighting position and orientation. Using the information obtained from light intensity and distribution analysis, our technique automatically generates HDR environment maps for virtual light sources via image interpolation. By applying the interpolated environment maps to an image-based lighting technique, we show that virtual light can create photo-realistically rendered images for graphic models.

• Broadcasting and Media Magazine
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• v.22 no.3
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• pp.69-75
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• 2017

SDR 영상과 함께 HDR 버전 제작을 함께 요청하는 프로젝트가 점점 늘어나는 추세다. 어느 정도 규모의 업체에서는 고가의 HDR 레퍼런스 모니터와 라이선스 비용을 지불하고 비교적 편리하게 작업할 수 있다. 상황이 그렇지 못할 경우 최소의 비용으로 장비를 구매하고, 기존 장비와 호환성을 점검하고, 컬러링 어플리케이션에서 지원하는 기능을 활용하여 최선의 워크플로를 구성해야 한다. 또한 SDR 버전을 HDR 버전으로 제작하거나 HDR 영상을 SDR 버전으로 변환할 때 장면마다 다시 보정하는 일을 최소화하기 위한 세심한 보정이 필요하다. 본 원고에서는 동시에 촬영된 BT.709 기반의 HD 프록시 영상과 RAW로 촬영된 UHD 원본 영상을 활용하여 변환 작업에서 주의 깊게 살펴보아야 할 사항들을 알아보도록 하겠다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.06a
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• pp.83-84
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• 2017

We propose a novel high dynamic range (HDR) video synthesis algorithm from alternatively exposed low dynamic range (LDR) videos. We first estimate correspondences between input fames using an illumination invariant descriptor. Then, we synthesize an HDR frame with the weights computed to maximize detail preservation in the output HDR frame. Experimental results demonstrate that the proposed algorithm provides high-quality HDR videos without noticeable artifacts.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.3
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• pp.81-89
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• 2012

Luminance is the most important quantity in lighting design and illuminating engineering. There are three methods for measuring luminance; using a conventional luminance meter, through the illuminance measurement and subsequent calculations and using digital imaging photometer. Recently, HDRI(High Dynamic Range Imaging) technique introduces a new method of capturing luminance values in a lighting environment. The radiance maps from HDRI are commonly used as visual environment maps for lighting analysis applications. For the HDRI, HDR software is needed to create HDR image. Currently, there is number of HDR software available. The purpose of this paper is to investigate whether a luminance map can be accurately captured by the various types of HDR software which include HDR Shop and Photoshop. To accomplish this goal a set of experiments was conducted. In order to assess the luminance values of the HDR image from HDR software, the values had to be compared to the ones obtained with conventional methods of luminance measurement.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.111-120
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• 2015

HDR(High dynamic range) imaging is a technique to represent a dynamic range of real world. Exposure fusion is a method to obtain a pseudo-HDR image and it directly fuses multi-exposure images instead of generating the true-HDR image. However, it results ghost artifacts while fusing the multi-exposure images with moving objects. To solve this drawback, temporal consistency assessment is proposed to remove moving objects. Firstly, multi-level threshold bitmap and brightness bitmap are proposed. In addition, hue-angle constancy map between multi-exposure images is proposed for compensating a bitmap. Then, two bitmaps are combined as a temporal weight map. Spatial domain image quality assessment is used to generate a spatial weight map. Finally, two weight maps are applied at each multi-exposure image and combined to get the pseudo-HDR image. In experiments, the proposed method reduces ghost artifacts more than previous methods. The quantitative ghost-free evaluation of the proposed method is also less than others.