• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.154-157
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• 2009

High dynamic range image can describe the real world scenes that have a wide range of luminance intensity. To display high dynamic range (HDR) image into conventional displayable devices such as monitors and printers, we proposed the logarithmic based global mapping algorithm that consider the features of image using mapping parameters. Based on characteristics of image, we first modify input luminance values for reproducing perceptually tuned images and then displayable output values are obtained directly. The experimental results show that the proposed algorithm achieves good subjective results while preserving details of image, furthermore proposed algorithm has fast simple and practical structure for implementation.

• 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.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.428-437
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• 2009

A high dynamic range (HDR) image can represent real world scenes that have a wide range of luminance intensity. However, compared with the range of real world luminance, conventional display devices have a low dynamic range (LDR). To display HDR images onto conventional displayable devices such as monitors and printers, we propose the logarithmic based global reproduction algorithm that considers the features of the image using reproduction parameters. Based on the characteristics of the image, we first modify the input luminance values for reproducing perceptually tuned images and then obtain the displayable output values directly. The experimental results show that the proposed algorithm achieves good subjective results while preserving details of the image; furthermore, the proposed algorithm has a fast, simple and practical structure for implementation.

• 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.

• Applied Microscopy
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• v.38 no.3
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• pp.185-193
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• 2008

An experimental comparison of the detection properties between imaging plate and film for recording the electron diffraction pattern was carried out on a radiation-sensitive material, an aluminum trihydroxide(gibbsite, ${\gamma}-Al(OH)_3$), through the electron beam irradiation. Because the imaging plate has a wide dynamic range sufficient for recording extremely low- and high-electron intensities, the range of spatial frequency for the diffraction pattern acquired by the imaging plate was extended to two times larger than the range by the film, especially at a low electron dose condition(${\leq}0.1\;e^-/{\mu}m^2$). It is also demonstrated that the imaging plate showed better resolving power for discriminating fine intensity levels even in saturated transmitted beam. Hence, in the respect of investigating the structures of radiation-sensitive materials and cryo-biological specimens, our experimental demonstrations suggest that the imaging plate technique may be a good choice for those studies, which have to use an extremely low electron intensity for recording.

• Journal of Korea Multimedia Society
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• v.22 no.1
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• pp.10-17
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• 2019

In High Dynamic Range (HDR) image processing, tone mapping is the process to compress an input image into a Low Dynamic Range (LDR) image. In most cases, the reason that detail preservation is prior to take over tone mapping is that the dynamic range is significantly different between input and output images. In the case of iCAM06, details are separated by using a bilateral filter, however, it causes noise amplification at the dim surround region. Thus, we suggest that the detail signal, which is separated from the bilateral filter, is combined with the base signal after an adaptive Kalman filter is applied according to the local standard deviation. We confirmed that the proposed method enhances the HDR images quality by checking the noise reduction in a dim surround region.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.137-140
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• 2021

High dynamic range (HDR) technology has been drawing attention in the field of imaging and consumer entertainment. As tools for capturing and creating HDR contents, encoding, and transmission evolve to support HDR formats, various display capabilities are being developed and increased. Hence, there is need for remapping native HDR imagery for display on lower quality legacy standard dynamic range (SDR) displays. This operation is referred to as tone mapping. In this paper, we present a sectional tone mapping method by Lenzen, and expand upon a tone mapping approach to improve temporal stability while maintaining picture quality. Compared to the existing block-based sectional tone mapping, our method uses the edge awareness-based tone mapping. We estimate the performance of the objective metric on temporal flickering. The experimental result shows that the algorithm maintains a smoother relationship between the output luminance values, and this reveals success in reducing halos and improving temporal stability with adopted edge aware filtering.

• Information Display
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• v.20 no.3
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• pp.3-9
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• 2019

본 논문에서는 HDR imaging 기술의 기본 원리와 전반적인 내용에 대해서 살펴보았다. 특히 최근 많은 관심을 받고 있는 딥러닝 기술에 대한 소개와 HDR imaging 기술에 어떤 형태로 적용되고 있는지에 대한 내용 및 최근 동향에 대해서도 함께 살펴보았다. HDR imaging 기술은 기존 디스플레이 대비 높은 인지 화질을 제공해주기 때문에 현재 많은 관심을 받고 있는 기술이며, 디스플레이 패널 기술 발전과 함께 지속적으로 연구되어야 하는 기술이다. 이와 관련해서 현재 많은 연구 기관 등에 대해서 관련 기술에 대해서 연구하고 있지만, 아직 많은 부분에 있어서 해결되어야 하겠다. 특히 궁극적으로 인간의 시각 특성을 고려한 영상 출력을 위해서는 디스플레이 기술 발전과 함께 알고리즘 측면에서 많은 연구가필요하겠다. 따라서 이러한 HDR imaging 기술을 포함한 다양한 알고리즘 개발을 통해서 현재보다 높은 수준의 실감형 디스플레이 기술 개발이 이루어질 것으로 기대된다.

• Journal of Broadcast Engineering
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• v.23 no.3
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• pp.369-382
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• 2018

We propose a single-shot high dynamic range (HDR) imaging algorithm using a deep convolutional neural network (CNN) for row-wise varying exposures in a single image. The proposed algorithm restores missing information resulting from under- and/or over-exposed pixels in an input image and reconstructs the raw radiance map. The main contribution of this work is the development of a loss function for the CNN employing the human visual system (HVS) properties. Then, the HDR image is obtained by applying a demosaicing algorithm. Experimental results demonstrate that the proposed algorithm provides higher-quality HDR images than conventional algorithms.