• Title, Summary, Keyword: 공간 필터

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A Study on the Spatial Weighted Filter in AWGN Environment (AWGN 환경에서 공간 가중치 필터에 관한 연구)

  • Long, Xu;Kim, Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.3
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    • pp.724-729
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    • 2013
  • Recently, with the popularization of digital devices, the requirements of image quality is becoming higher and higher. However, the images are frequently corrupted in the image data processing, there are several reasons for this and the noise is considered as the main reason. Therefore, in order to alleviate the influence of AWGN(additive white Gaussian noise) in image, this paper puts forward the spatial weighted filtering algorithm. The algorithm set the weighted value according to the spatial distance, compared with the existing methods. The algorithm not only alleviated the influence of AWGN effectively but also reserved image details.

Image Quality Improvement in Computed Tomography by Using Anisotropic 2-Dimensional Diffusion Based Filter (비등방성 2차원 확산 기반 필터를 이용한 전산화단층영상 품질 개선)

  • Seoung, Youl-Hun
    • Journal of the Korean Society of Radiology
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    • v.10 no.1
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    • pp.45-51
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    • 2016
  • The purpose of this study was tried to remove the noise and improve the spatial resolution in the computed tomography (CT) by using anisotropic 2-dimensional (2D) diffusion based filter. We used 4-channel multi-detector CT and american association of physicists in medicine (AAPM) phantom was used for CT performance evaluation to evaluate the image quality. X-ray irradiation conditions for image acquisition was fixed at 120 kVp, 100 mAs and scanned 10 mm axis with ultra-high resolution. The improvement of anisotropic 2D diffusion filtering that we suggested firstly, increase the contrast of the image by using histogram stretching to the original image for 0.4%, and multiplying the individual pixels by 1.2 weight value, and applying the anisotropic diffusion filtering. As a result, we could distinguished five holes until 0.75 mm in the original image but, five holes until 0.40 mm in the image with improved anisotropic diffusion filter. The noise of the original image was 46.0, the noise of the image with improved anisotropic 2D diffusion filter was decreased to 33.5(27.2%). In conclusion improved anisotropic 2D diffusion filter that we proposed could remove the noise of the CT image and improve the spatial resolution.

Proximate Word Filtering by Hierarchical Clustering (계층적 군집화를 이용한 근사 단어 필터링 기법)

  • Kim, Sung-Hwan;Cho, Hwan-Gue
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1101-1104
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    • 2012
  • 단어 필터링은 유해정보를 차단위한 기본적인 기능이다. 그러나 악의적인 사용자는 필터링 시스템을 우회하기 위하여 금지 단어에 의도적인 변형을 가한다. 이에 대응하기 위해 일정 오류를 허용하여 필터링을 수행하는 근사 단어 필터링이 있다. 근사 단어를 검색하기 위한 문자열 색인 방법으로는 주로 기준 단어(Pivot)을 이용한 유클리드 공간에의 사상을 이용하는데, 이는 단어 필터링에 응용하기에는 근본적인 구조상의 한계점이 있다. 본 논문에서는 필터링 대상이 되는 단어 집합 내에서 군집화를 수행하여 계층적인 자료구조를 구성하고, 단어 필터링을 위한 필터링 질의(Filtering query)를 정의한 뒤 그에 적합한 탐색 상의 적용에 관하여 설명한다. 실험 결과 기존의 기준 단어(Pivot)을 이용한 색인 기법에 비하여 16.9%~26.6%의 탐색 속도 향상을 확인할 수 있었다.

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The Line Feature Extraction for Automatic Cartography Using High Frequency Filters in Remote Sensing : A Case Study of Chinju City (위성영상의 형태추출을 통한 지도화 : 고빈도 공간필터 사용을 중심으로)

  • Jung, In-Chul
    • Journal of the Korean association of regional geographers
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    • v.2 no.2
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    • pp.183-196
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    • 1996
  • The purpose of this paper is to explore the possibility of automatic extraction of line feature from Satellite image. The first part reviews the relationship between spatial filtering and cartographic interpretation. The second part describes the principal operations of high frequency filters and their properties, the third part presents the result of filtering application to the SPOT Panchromatic image of the Chinju city. Some experimental results are given here indicating the high feasibility of the filtering technique. The results of the paper is summarized as follows: Firstly the good all-purposes filter dose not exist. Certain laplacian filter and Frei-chen filter were very sensitive to the noise and could not detect line features in our case. Secondly, summary filters and some other filters do an excellent job of identifying edges around urban objects. With the filtered image added to the original image, the interpretation is more easy. Thirdly, Compass gradient masks may be used to perform two-dimensional, discrete differentiation directional edge enhancement, however, in our case, the line featuring was not satisfactory. In general, the wide masks detect the broad edges and narrow masks are used to detect the sharper discontinuities. But, in our case, the difference between the $3{\times}3$ and $7{\times}7$ kernel filters are not remarkable. It may be due to the good spatial resolution of Spot scene. The filtering effect depends on local circumstance. Band or kernel size selection must be also considered. For the skillful geographical interpretation, we need to take account the more subtle qualitative information.

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Implementation of Real-time Transaural Filter for 3D Sound Reproduction (입체 음향 재생을 위한 실시간 트랜스오럴 필터 구현)

  • 이동우
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.269-272
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    • 1998
  • 본 논문에서는 스테레오 스피커를 통해 입체 음향을 재생할 때 발생하는 크로스 토크(corss talk)를 제거하기 위한 트랜스오럴 필터를 실시간으로 구현하였다. 실시간 처리를 위하여 일반적인 트랜스오럴 필터를 재구성하였으며, 범용 DSP(Digital Signal Processor) 칩인 TMS320C40을 사용하였다. 메인 프로그램은 C-언어를 이용하여 작성하였으며, 빠른 연산을 필요로 하는 컨벌루션 함수는 어셈블러 언어를 이용하여 최적화 하였다. 구현된 트랜스오럴 필터의 평가를 위해서 더미 헤드를 이용하여 녹음된 binaural 신호와 DSP를 이용하여 실시간으로 합성된 binaural 신호를 스테레오 스피커를 통해 재생하여 청취 실험하였다. 청취 실험한 결과 머리 밖에서 음상 정위가 이루어지고 공간감과 거리감은 헤드폰으로 청취할 때 보다 우수하게 나타났다.

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HEVC 기반 스케일러블 비디오 압축을 위한 보간 필터

  • Kim, Gyeong-Hye;Nam, Jeong-Hak;Sim, Dong-Gyu
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.167-169
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    • 2012
  • 스케일러블 비디오 압축 기술 중 공간적 스케일러빌리티 기술에는 계층 간의 예측을 위해서 참조 계층의 영상을 향상 계층의 해상도와 동일하게 하는 영상 보간 과정이 필요하다. 본 논문에서는 HEVC (high efficiency video coding) 기반의 스케일러블 비디오 압축을 위하여 새로운 영상 보간 필터를 제안한다. 제안하는 보간 필터는 DCT (discrete cosine transform) 수식을 기반으로 설계되었으며, 하위 계층의 텍스처를 1.5 배로 보간할 때 사용된다. 제안하는 보간 필터를 적용하여 계층 간 예측을 수행할 결과, simulcast 로 부호화 한 것 대비 BD-bitrate 를 약 52.8% 감소시켰고, BD-PSNR 을 약 1.87dB 증가시켰다.

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Robust Multi-channel Wiener Filter for Suppressing Noise in Microphone Array Signal (마이크로폰 어레이 신호의 잡음 제거를 위한 강인한 다채널 위너 필터)

  • Jung, Junyoung;Kim, Gibak
    • Journal of Broadcast Engineering
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    • v.23 no.4
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    • pp.519-525
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    • 2018
  • This paper deals with noise suppression of multi-channel data captured by microphone array using multi-channel Wiener filter. Multi-channel Wiener filter does not rely on information about the direction of the target speech and can be partitioned into an MVDR (Minimum Variance Distortionless Response) spatial filter and a single channel spectral filter. The acoustic transfer function between the single speech source and microphones can be estimated by subspace decomposition of multi-channel Wiener filter. The errors are incurred in the estimation of the acoustic transfer function due to the errors in the estimation of correlation matrices, which in turn results in speech distortion in the MVDR filter. To alleviate the speech distortion in the MVDR filter, diagonal loading is applied. In the experiments, database with seven microphones was used and MFCC distance was measured to demonstrate the effectiveness of the diagonal loading.

Automatic Identification of Fiducial Marks Existing on Aerial Photographs (항공사진에 포함된 기점 마크의 자동 인식)

  • 조성익;방기인
    • Proceedings of the Korean Information Science Society Conference
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    • pp.556-558
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    • 2002
  • 항공사진에 포함된 기점 마크의 방사 및 기하 특성을 이용하여 마크의 중심 위치를 자동으로 인식하기 위한 방안을 제안한다. 마크를 포함하는 배경 영역의 방사 특성에 기반을 푼 전략에 근거하여 입력된 영상을 이치화한 다음 형태 연산자를 적용시켜 기전 마크가 있는 후보 영역을 추출한다. 기하 특성에 기반을 둔 전략에 근거하여 ▽$^2$G 필터링과 대칭성 강조 필터링을 적용시킨 후, 대칭이 가장 강하게 나타나는 위치인 마크의 중심 위치를 구한다. 66매의 기점 마크 영상에 대한 평가 결과 중심 위치가 1 화소의 정확도까지 얻어질 수 있다는 것을 확인할 수 있었다.

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Pre-Filtering based Post-Load Shedding Method for Improving Spatial Queries Accuracy in GeoSensor Environment (GeoSensor 환경에서 공간 질의 정확도 향상을 위한 선-필터링을 이용한 후-부하제한 기법)

  • Kim, Ho;Baek, Sung-Ha;Lee, Dong-Wook;Kim, Gyoung-Bae;Bae, Hae-Young
    • Journal of Korea Spatial Information System Society
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    • v.12 no.1
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    • pp.18-27
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    • 2010
  • In u-GIS environment, GeoSensor environment requires that dynamic data captured from various sensors and static information in terms of features in 2D or 3D are fused together. GeoSensors, the core of this environment, are distributed over a wide area sporadically, and are collected in any size constantly. As a result, storage space could be exceeded because of restricted memory in DSMS. To solve this kind of problems, a lot of related studies are being researched actively. There are typically 3 different methods - Random Load Shedding, Semantic Load Shedding, and Sampling. Random Load Shedding chooses and deletes data in random. Semantic Load Shedding prioritizes data, then deletes it first which has lower priority. Sampling uses statistical operation, computes sampling rate, and sheds load. However, they are not high accuracy because traditional ones do not consider spatial characteristics. In this paper 'Pre-Filtering based Post Load Shedding' are suggested to improve the accuracy of spatial query and to restrict load shedding in DSMS. This method, at first, limits unnecessarily increased loads in stream queue with 'Pre-Filtering'. And then, it processes 'Post-Load Shedding', considering data and spatial status to guarantee the accuracy of result. The suggested method effectively reduces the number of the performance of load shedding, and improves the accuracy of spatial query.

An Open Source Mobile Cloud Service: Geo-spatial Image Filtering Tools Using R (오픈소스 모바일 클라우드 서비스: R 기반 공간영상정보 필터링 사례)

  • Kang, Sanggoo;Lee, Kiwon
    • Spatial Information Research
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    • v.22 no.5
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    • pp.1-8
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    • 2014
  • Globally, mobile, cloud computing or big data are the recent marketable key terms. These trend technologies or paradigm in the ICT (Information Communication Technology) fields exert large influence on the most application fields including geo-spatial applications. Among them, cloud computing, though the early stage in Korea now, plays a important role as a platform for other trend technologies uses. Especially, mobile cloud, an integrated platform with mobile device and cloud computing can be considered as a good solution to overcome well known limitations of mobile applications and to provide more information processing functionalities to mobile users. This work is a case study to design and implement the mobile application system for geo-spatial image filtering processing operated on mobile cloud platform built using OpenStack and various open sources. Filtering processing is carried out using R environment, recently being recognized as one of big data analysis technologies. This approach is expected to be an element linking geo-spatial information for new service model development and the geo-spatial analysis service development using R.