• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1858-1859
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• 2007

최근 LCD-TV의 화질 개선을 위해서 다양한 영상처리 알고리즘이 적용되고 있다. 그 중 선명도 개선 알고리즘은 영상의 경계선을 강조하여 영상이 보다 선명하게 보이도록 한다. 하지만 경계선을 강조하는 과정에서 노이즈도 같이 증가하는 문제점이 있다. 본 논문에서는 강조된 경계선을 유지하면서 노이즈를 줄일 수 있는 알고리즘을 제안하고자 한다. 이를 위하여 Bilateral 필터를 기반으로 영상의 분산 값에 따라 영상의 노이즈 제거 정도를 결정하는 알고리즘을 제안한다.

• Journal of Korea Game Society
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• v.9 no.2
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• pp.135-142
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• 2009

Mesh denoising is a method to remove noise applying various filters. However, those methods usually spend much time since filtering is performed on CPU. Because GPU is specialized for floating point operations and faster than CPU, real-time processing for complex operations is possible. Especially mesh denoising is adequate for GPU parallel processing since it repeats the same operations for vertices or triangles. In this paper, we propose mesh denoising algorithm based on bilateral filtering using GPU parallel processing to reduce processing time. It finds neighbor triangles of each vertex for applying bilateral filter, and computes its normal vector. Then it performs bilateral filtering to estimate new vertex position and to update its normal vector.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.344-346
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• 2016

본 논문에서는 양방향 필터와 (bilateral filter) 선형 사상 함수를 (linear mapping function) 이용한 역 톤매핑 (inverse tone mapping, iTMO) 알고리즘을 제안한다. 상용 HDR (high dynamic range) 디스플레이가 (display device) 보급됨에 따라 이미 존재하는 수 많은 LDR (low dynamic range) 영상을 활용하여 HDR 디스플레이에서 시청할 수 있도록 동적 범위를 (dynamic range) 확장하는 (expand) 역 톤 매핑 방법이 개발 되어야 한다. 여러 논문을 통해 다양한 역 톤 매핑 방법이 제안되어 왔는데, 대부분의 방법이 HDR 디스플레이의 동적 범위에 맞춰 LDR 영상의 동적 범위를 확장하는 것에 그쳤다. 확장하는 방법은 다양하지만, 동적 범위의 한계로 인해 LDR 영상에서 사라진 세부 사항을 (detail) 복원하는 것에는 전혀 효과적이지 않았다. 이에 본 논문에서는 LDR 영상의 동적 범위를 확장하는 것뿐만 아니라 LDR 영상에서 표현되지 못한 디테일을 복원하는 방법을 제안한다. 이를 위해 입력 영상에 양방향 필터를 적용하여 영상을 기본 계층과 (base layer) 세부 계층으로 (detail layer) 분해한 후 기본 계층에 대해서는 동적 범위에 맞게 확장하고, 세부 계층에 대해서는 디테일을 복원하기 위해 선형 사상 함수를 적용하였다. 실험을 통해서 다른 iTMO 방법에 비해 세부 사항을 효과적으로 복원할 수 있음을 확인할 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.87-97
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• 1998

This paper describes an analysis of tunable characteristic for magnetically tunable E-plane type finline filter on a ferrite substrate. The proposed design is based on using of quarter wavelength transmission line for compensating the negative length transmission line of end K-inverters of E-plane type waveguide filters and the tunable characteristics of designed filters are analyzed. The analysis results of filter and inverter structure loaded with finline on a ferrite substrate are obtained using the edge based finite element method including higher order mode effects. The X-band experimental results for bilateral and unilateral finline magnetically tunable E-plane type waveguide filters agree well with the simulated data.

• Journal of Korea Game Society
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• v.15 no.2
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• pp.159-168
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• 2015

This paper introduces effective noise removal method for medical ultrasound volume data. Ultrasound volume data need to be filtered because it has a lot of noise. Conventional 2d filtering methods ignore information of adjacent layers and conventional 3d filtering methods are slow or have simple filter that are not efficient for removing noise and also don't equally operate filtering because that don't take into account ultrasound' sampling character. To solve this problem, we introduce method that fast perform in parallel bilateral filtering that is known as good for noise removal and adjust proportionally window size depending on that's position. Experiments compare noise removal and loss of original data among average filtered or biliteral filtered or adaptive biliteral filtered ultrasound volume rendering images. In this way, we can more efficiently and correctly remove noise of ultrasound volume data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.137-143
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• 2017

X-ray image is a widely used to medical examination, airport security and cargo inspection. However, X-ray images contain many visual noise, which interrupt image analysis. Consequently, it is primary importance to reduce noises of X-ray image. In this paper, we present a improved denoise technique for x-ray image using pixel value and range weights. First, we denoise a x-ray image using bilateral filter. Next, we detect a edge region of the original x-ray image. If a denoised pixel belongs to the edge region, we calculate weighting values of original x-ray image and denoised x-ray image in $3{\times}3$ neighboring pixels and compute the cost value to determine the boundary pixel value. Finally, the pixel value having minimum cost is determined as the pixel value of the denoised x-ray image. Simulation results show that the proposed algorithm achieves good performance in terns of PSNR comparison and subjective visual quality.

• Korean Journal of Remote Sensing
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• v.36 no.4
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• pp.503-513
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• 2020

This paper presents a method to evaluate denoising filters based on edge locations in their denoised images. Image quality assessment has often been performed by using structural similarity (SSIM). However, SSIM does not provide clearly the geometric accuracy of features in denoised images. Thus, in this paper, a method to localize edge locations with subpixel accuracy based on adaptive weighting of gradients is used for obtaining the subpixel locations of edges in ground truth image, noisy images, and denoised images. Then, this paper proposes a method to evaluate the geometric accuracy of edge locations based on root mean squares error (RMSE) and jaggedness with reference to ground truth locations. Jaggedness is a measure proposed in this study to measure the stability of the distribution of edge locations. Tested denoising filters are anisotropic diffusion (AF), bilateral filter, guided filter, weighted guided filter, weighted mean of patches filter, and smoothing filter (SF). SF is a simple filter that smooths images by applying a Gaussian blurring to a noisy image. Experiments were performed with a set of simulated images and natural images. The experimental results show that AF and SF recovered edge locations more accurately than the other tested filters in terms of SSIM, RMSE, and jaggedness and that SF produced better results than AF in terms of jaggedness.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.10-13
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• 2012

본 논문은 가상 직물 착용을 위한 직조 패턴 제거 필터의 성능 분석에 관한 것이다. 명도 차분 맵을 이용한 가상 직물 착용 시스템은 의류 형상 영역의 명도 차분 맵을 이용하여 조명과 음영 특성을 추출할 시, 의류 형상 영역의 색상에는 무관하지만 의류 모델의 직조 패턴에는 영향을 받는다. 본 논문에서는 바이래터럴 필터(bilateral filter)와 측지 형태학 필터(geodesic morphological filter)에 기반하여 모델 의류 영역의 직조 패턴을 제거하는 방법을 소개하고 그 성능을 분석함에 목적이 있다. 가상 직물 착용 시스템에 직조 패턴 제거 필터를 채택할 경우, 최대한 모델 영상의 직조 패턴에 무관하게 직물 원단의 디자인이 의복의 외관에 미치는 영향을 시뮬레이션할 수 있음에 따라 직물 디자이너의 창작활동을 도와줄 수 있다. 또한 온라인상에서 직물 원단이나 의류를 거래할 시에 구매자로 하여금 모델 영상의 직조패턴에 종속되지 않은 상태에서 의사결정을 할 수 있도록 지원해 B2B 또는 B2C 전자상거래 행위를 촉진할 수 있다.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.439-441
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• 2005

A kernel regression filter with adaptive bandwidth is developed and successfully applied to digital reactivity meter for neutron signal measurement in nuclear reactors. The purpose of this work is not only reduction of the measurement noise but also the edge preservation of the reactivity signal. The performance of the filtering algorithm is demonstrated comparing with well known smoothing methods of conventional low-pass and bilateral filters. The developed method gives satisfactory filtering performance and edge preservation capability.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.933-944
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• 2012

In this paper, we propose a new method to convert a low-resolution depth map into its high-resolution one called distance transform-based bilateral upsampling. Since the proposed method controls the spatial domain weighting function based on distance transform values of the depth map, it increases the input depth map resolution while preserving edge sharpness. The proposed method is composed of three main steps: distance transform, spatial weighting control, and image interpolation. Experimental results show that our method outperforms the conventional bilateral upsampling in terms of the quality of output depth maps.