• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.377-382
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• 1997

멀티미디어가 발달함에 딸 이를 위한 다양한 검색 기법들이 제안되고 있다. 본 논문에서는 WeCAM 시스템에서 비디오 검색을 하기 위한 텍스처 성분과 영상의 윤곽선 특징을 동시에 이용한 검색 기법을 제안한다. 텍스처 특성 추출에는 8$\times$8 블록 DCT를 기반으로한 DCT-par와 DCT-energy 기법을 적용하고 윤곽선 추출에는 DCT의 대각선 계수를 이용하는 기법을 이용한다. WebCAM으로 생성된 비디오는 MPEG표준을 따르는 것으로 가정하고 있으며, 압축된 데이터에 디코딩 과정없이 직접 검색 기법을 적용함으로써 처리 시간을 단축할수 있다는 장점이 있다.

• Korean Journal of Remote Sensing
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• v.31 no.3
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• pp.255-265
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• 2015

Very high resolution (VHR) satellite imagery provide valuable information on urban change monitoring due to multi-temporal observation over large areas. Recently, there has been increased interest in the urban change detection technique using VHR Synthetic Aperture Radar (SAR) imaging system, because it can take images regardless of solar illumination and weather condition. In this paper, we proposed a texture-based urban change detection method using the VHR SAR texture features generated from Gray-Level Co-Occurrence Matrix (GLCM). In order to evaluate the efficiency of the proposed method, the result was compared, visually and quantitatively, with the result of Non-Coherent Change Detection (NCCD) which is widely used for the change detection of VHR SAR image. The experimental results showed the greater detection accuracy and the visually satisfactory result compared with the NCCD method. In conclusion, the proposed method has shown a great potential for the extraction of urban change information from VHR SAR imagery.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.545-556
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• 2015

A HEVC-compatible 3D video coding method (3D-HEVC) has been recently developed as an extension of the high efficiency video coding (HEVC) standard. In order to efficiently deal with the multi-view video plus depth (MVD) format, 3D-HEVC exploits an inter-component prediction which allows the prediction between texture and depth map images in addition to a temporal prediction used in the conventional single layer video coding such as H.264/AVC and HEVC. The performance of the inter-component prediction is normally affected by the accuracy of the disparity vector, and thus it is important to have an accurate disparity vector used for the inter-component prediction. This paper, therefore, introduces a disparity derivation method and inter-component algorithms using the disparity vector for the efficient 3D video coding. Simulation results show that the 3D-HEVC provides higher coding performance compared with the simulcast approach using HEVC and the simple multi-view extension (MH-HEVC).

• Journal of the Korea Computer Graphics Society
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• v.14 no.1
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• pp.17-25
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• 2008

We proposed the method for photomosaic generation using a programmable GPU. We design vertices to generate a photomosaic through a graphics pipeline and suggest a texture representation of an image database whice is used for tile. Both the source image and the tiles are stored to texture, which are matched by a vertex shader and drawn by a fragment shader. This is much faster than several techniques which achieve the best match for each tile.

• Journal of the Korea Computer Graphics Society
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• v.11 no.4
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• pp.34-38
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• 2005

본 논문에서는 대형 스크린 기반 디스플레이 환경에서 시각 커뮤니케이션 증진을 위한 비디오 아바타 생성 기법에 대하여 소개한다. 일반적으로 대형 스크린 기반 가상 환경에서는 스크린으로 투사되는 빛의 변화 때문에 정적 배경을 보장할 수 없다. 뿐만 아니라 카메라 위치 설정이 자유롭지 못하기 때문에 디스플레이 환경 내에 있는 사용자를 대상으로 비디오 아바타를 생성하기 쉽지 않다. 본 논문에서는 적외선 및 필터를 이용하여 가시광선을 차단함으로써 사용자 영역을 쉽게 정의할 수 있도록 하였고, 나란히 배치된 컬러 영상에 실루엣 마스크를 적합하여 배경이 제거된 사용자 컬러 영상을 추출할 수 있도록 하였다. 또한 생성된 스테레오 비디오 아바타 영상은 투영 텍스처를 이용하여 보정된 후 가상세계에 투사되어 입체 디스플레이 된다. 제안된 기법은 일반적인 카메라를 이용하고 있으며, 간단한 조명 조건만 설정해주면 기존의 대형 스크린 기반 프로젝션 환경을 변형하지 않고도 쉽게 설치하여 사용할 수 있기 때문에 많은 활용도가 있을 것이라 기대된다.

• Journal of the Korean Society of Radiology
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• v.82 no.1
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• pp.116-127
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• 2021

Purpose To evaluate the feasibility of texture analysis of gray-scale ultrasound (US) images for staging of hepatic fibrosis. Materials and Methods Altogether, 167 patients who had undergone routine US and laboratory tests for a fibrosis-4 (FIB-4) index were included. Texture parameters were measured using a dedicated in-house software. Regions of interest were placed in five different segments (3, 5, 6, 7, 8) for each patient. The FIB-4 index was used as the reference standard for hepatic fibrosis grade. Comparisons of the texture parameters between different fibrosis groups were performed with the Student's t-test or Mann-Whitney U-test. Diagnostic performance was evaluated by receiver operating curve analysis. Results The study population comprised of patients with no fibrosis (FIB-4 < 1.45, n = 50), mild fibrosis (1.45 ≤ FIB-4 ≤ 2.35, n = 37), moderate fibrosis (2.35 < FIB-4 ≤ 3.25, n = 27), and severe fibrosis (FIB-4 > 3.25, n = 53). Skewness in hepatic segment 5 showed a difference between patients with no fibrosis and mild fibrosis (0.2392 ± 0.3361, 0.4134 ± 0.3004, respectively, p = 0.0109). The area under the curve of skewness for discriminating patients with no fibrosis from those with mild fibrosis was 0.660 (95% confidence interval, 0.551-0.758), with an estimated accuracy, sensitivity, specificity of 64%, 87%, 48%, respectively. Conclusion A significant difference was observed regarding skewness in segment 5 between patients with no fibrosis and patients with mild fibrosis.

• Journal of the Korea Society of Computer and Information
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• v.16 no.3
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• pp.27-34
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• 2011

In this paper, the novel approach for image contrast enhancement is introduced. The method is based on the unsharp mask and directional information of images. Since the unsharp mask techniques give better visual quality than the conventional sharpening mask, there are much works on image enhancement using unsharp masks. The proposed algorithm decomposes the image to several blocks and extracts directional information using DCT. From the geometric properties of the block, each block is labeled as appropriate type and processed by adaptive unsharp mask. The masking process is skipped at the flat area to reduce the noise artifact, but at the texture and edge area, the adaptive unsharp mask is applied to enhance the image contrast based on the edge direction. Experiments show that the proposed algorithm produces the contrast enhanced images with superior visual quality, suppressing the noise effects and enhancing edge at the same time.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.427-439
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• 2019

Purpose: We generated geospatial information of unmanned aerial vehicle based on various SW and analyzed the location accuracy of orthoimage and DSM and texture mapping of 3D mesh. Method: The same unmanned aerial image data is processed using two different SW, and spatial information is generated. Among the generated spatial information, the orthoimage and DSM were compared with the spatial information generation results of the unmanned aerial photogrammetry SW by performing quantitative analysis by calculating RMSE of horizontal position and vertical position error and performing qualitative analysis. Results: There were no significant differences in the positional accuracy of the orthoimage and DSM generated by each SW, and differences in texture mapping in 3D mesh. The creation of the 3D mesh indicated the impact of the Unmanned Aerial Photogrammetry SW. Conclusion: It is shown that there is no effect of SW on the creation of orthoimage and DSM for geospatial analysis based on unmanned aerial vehicle. However, when 3D visualization is performed, texture mapping results are different depending on SW.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.1
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• pp.41-48
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• 2009

This Paper introduces representation and coding schemes of multiview texture and depth data for complex three-dimensional scenes. We represent input color and depth images using compressed texture and depth map pairs. The proposed X-codec encodes them further to increase compression ratio in a near-lossless way. Our system resolves two problems. First, rendering time and output visual quality depend on input image resolutions rather than scene complexity since a depth image-based rendering techniques is used. Second, the random access problem of conventional image-based rendering could be effectively solved using our image block-based compression schemes. From experimental results, the proposed approach is useful to graphics applications because it provides multiview rendering, selective decoding, and scene manipulation functionalities.

• Journal of Broadcast Engineering
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• v.13 no.3
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• pp.339-349
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• 2008

We present a novel method to estimate the light source direction and relight a face texture image of a single 3D model under arbitrary unknown illumination conditions. We create a virtual irradiance sphere to detect the light source direction from a given illuminated texture image using both normal vector mapping and weighted bilinear interpolation. We then induce a relighting equation with estimated ambient and diffuse coefficients. We provide the result of a series of experiments on light source estimation, relighting and face recognition to show the efficiency and accuracy of the proposed method in restoring the shading and shadows areas of a face texture image. Our approach for face relighting can be used for not only illuminant invariant face recognition applications but also reducing visual load and Improving visual performance in tasks using 3D displays.