• Title/Summary/Keyword: 위너필터링

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Image Restoration Based on Inverse Filtering Order and Power Spectrum Density (역 필터 순서와 파워 스펙트럼 밀도에 기초한 이미지 복원)

  • Kim, Yong-Gil;Moon, Kyung-Il
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.2
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    • pp.113-122
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    • 2016
  • In this paper, we suggest a approach which comprises fast Fourier transform inversion by wavelet noise attenuation. It represents an inverse filtering by adopting a factor into the Wiener filtering, and the optimal factor is chosen to minimize the overall mean squared error. in order to apply the Wiener filter, we have to compute the power spectrum of original image from the corrupted figure. Since the Wiener filtering contains the inverse filtering process, it expands the noise when the blurring filter is not invertible. To remove the large noises, the best is to remove the noise using wavelet threshold. Wavelet noise attenuation steps are consisted of inverse filtering and noise reduction by Wavelet functions. experimental results have not outperformed the other methods over the overall restoration performance.

Wavelet Domain Image Denoising by using Cross-shaped Wiener Filter (Cross-shaped 위너 필터를 이용한 웨이블릿 기반의 이미지 잡음 제거)

  • Yoo, Jong-Sang;Lee, Kyung-Jun;Jeong, Je-Chang
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2012.11a
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    • pp.122-124
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    • 2012
  • 잡음이 존재하는 환경에서의 신호의 분산을 측정하는 것은 잡음 제거에 중요한 요소를 맡고 있다. 잡음을 제거하는 방법 중에 가장 보편적으로 사용하는 방법에는 위너 필터가 존재한다. 웨이블릿 기반의 위너 필터링은 저복잡성을 지닌 이미지 잡음 제거에 탁월한 효과를 보인다. 신호의 분산을 측정할 경우 어떤 모양의 필터를 적용하여 측정하느냐에 따라 분산이 달라지게 되므로 이미지의 잡음 제거에 영향을 미치게 된다. 이에 본 논문은 위너 필터에 적용되는 필터를 기존의 정사각형 모양(square-shaped)과 제안하는 십자가 모양(cross-shaped)을 각각 적용하여 이미지의 잡음을 제거하였다.

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A Restoration of Degraded Medicine Images Based on Optimized Parametric Wiener Filter (최적화된 매개변수 위너필터를 이용한 훼손된 의료영상의 복원)

  • Shin, Choong-Ho;Jung, Chai-Yeoung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.5
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    • pp.1055-1063
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    • 2012
  • The noise of image is added by many environmental factors. Therefore, we need to remove these noises using the conventional filtering methods, which are optimized based on the statistical characteristic of noise. In direct restoration method, there is an inverse filter and the wiener filter. Here, the wiener filter is the optimized filter in the view of least square method. First, we are going to study the inverse filter, wiener filter, constraint least square filter. Second, in order to control the quantity, we use the parameters instead of the power spectrum ratio. But, these parameters have the conflicting condition, therefore, we optimized the variables using parametric wiener filter which adjust the application appropriately. In the simulation results, the contrast of the degraded image was enhanced and the noise was removed. Comparative experimentation was demonstrated edge preserving and noise removing property.

Performance Analysis of GHICW(Group-wise Hybrid Interference Cancellation scheme based on Wiener filtering) in Multi Rate DS/CDMA System (그룹형 하이브리드 위너 필터링 간섭제거 기법을 이용한 다중 데이터 율 DS/CDMA 시스템의 성능분석)

  • 최원태;박상규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.8B
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    • pp.1176-1182
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    • 2001
  • 본 논문에서는 서로 다른 데이터 율 신호들의 다중 접속 간섭을 제거하기 위해 그룹형 하이브리드 위너 필터링 간섭 제거 기법(Group-wise Hybrid Interference Cancellation scheme based on Wiener filtering : GHICW)을 제안하고 AWGN 채널과 레일리 페이딩 채널환경에서 그 성능을 상용검파기와 비교 분석하였다. 본 논문에서 제시한 수신 기법은 동일 데이터 율을 가진 사용자를 그룹으로 묶어 처리함으로써 기존의 간섭제거 시스템보다 시스템 처리 지연이 적고, 하드웨어 구현이 간단하며, 큰 전력으로 전송되는 높은 데이터 율 사용자의 신호들을 위너 필터를 이용해 재생하여 낮은 데이터 율 사용자와 높은 데이터 율 사용자의 수신 성능을 향상시킨다.

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Wiener filtering-based ambient noise reduction technique for improved acoustic target detection of directional frequency analysis and recording sonobuoy (Directional frequency analysis and recording 소노부이의 표적 탐지 성능 향상을 위한 위너필터링 기반 주변 소음 제거 기법)

  • Hong, Jungpyo;Bae, Inyeong;Seok, Jongwon
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.2
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    • pp.192-198
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    • 2022
  • As an effective weapon system for anti-submarine warfare, DIrectional Frequency Analysis and Recording (DIFAR) sonobuoy detects underwater targets via beamforming with three channels composed of an omni-direcitonal and two directional channels. However, ambient noise degrades the detection performance of DIFAR sonobouy in specific direction (0°, 90°, 180°, 270°). Thus, an ambient noise redcution technique is proposed for performance improvement of acoustic target detection of DIFAR sonobuoy. The proposed method is based on OTA (Order Truncate Average), which is widely used in sonar signal processing area, for ambient noise estimation and Wiener filtering, which is widely used in speech signal processing area, for noise reduction. For evaluation, we compare mean square errors of target bearing estmation results of conventional and proposed methods and we confirmed that the proposed method is effective under 0 dB signal-to-noise ratio.

A Study on Image Restoration using Mean and Wiener Filter (평균 및 위너 필터를 사용한 영상 복원에 관한 연구)

  • Moon Hong-Deuk;Kang Kyeong-Deog;Bae Sang-Bum;Kim Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.7
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    • pp.1393-1398
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    • 2004
  • Image is degraded by several causes such as the process of acquisition, storage and transmission. To restore those images, many researches have been continued. Centrally methods to restore degraded image by AWGN(additive white gaussian noise) a.e mean filter and wiener filter. Especially, mean filter is superior in noise reduction of area that is a small change of luminosity. But mean filter brings about the effect smoothing edge components of the image, because it does'nt consider characteristics of the image. So in this paper we propose an image restoration method compounding respective images adding established weights, after filtering with mean filter and powerful wiener filter in both improvement of contrast and preservation of edge components.

An Efficient Iterative Receiver for OFDMA Systems in Uplink Environments (직교 주파수 분할 다중 접속 시스템 상향 전송에 알맞은 효율적인 반복 수신 기법)

  • Hwang, Hae-Gwang;Sang, Young-Jin;Byun, Il-Mu;Kim, Kwang-Soon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.11 s.353
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    • pp.8-15
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    • 2006
  • In this paper, we propose the iterative receiver for LDPC-coded OFDMA systems in uplink environments. Applying the Wiener filtering to pilot symbols, an initial channel estimation can be performed effectively. To reduce the complexity of the Wiener filtering, we approximate Wiener filtering coefficients to pre-determined coefficients according to estimated correlation of channel. After an LDPC decoding process, soft symbol derived by extrinsic information of decoder outputs is used to estimate channel. we also derive the error variance of channel estimation and maximum ratio combined results. Using combined results, the channel correlation is re-estimated. Then the proper Wiener filtering coefficients are chosen according to the re-estimated result of the channel correction. Using a computer simulation, we show that the proposed receiver structure has the better performance than the receiver using only pilot symbols.

Enhancement of Evoked Potential Waveform using Delay-compensated Wiener Filtering (지연보상 위너 필터링에 의한 유발전위 파형개선)

  • Lee, JeeEun;Yoo, Sun K.
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.12
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    • pp.261-269
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    • 2013
  • In this paper, the evoked potential(EP) was represented by additive delay model to comply with the variational noisy response of stimulus-event synchronization. The hybrid method of delay compensated-Wiener filtered-ensemble averaging(DWEA) was proposed to enhance the EP signal distortion occurred during averaging procedure due to synchronization timing mismatch. The performance of DWEA has been tested by surrogated simulation, which is composed of synthesized arbitrary delay and arbitrary level of added noise. The performance of DWEA is better than those of Wiener filtered-ensemble averaging and of conventional ensemble averaging. DWEA is endurable up to added noise gain of 7 for 10 % mean square error limit. Throughout the experimentation observation, it has been demonstrated that DWEA can be applied to enhance the evoked potential having the synchronization mismatch with added noise.

Separation of Heart Sounds and Lung Sounds Using Adaptive Lattice Wiener Filter (적응 격자 위너 필터를 이용한 폐음과 심음의 분리)

  • Lee, Sang-Hun;Kim, Geun-Seop;Lee, Jin;Hong, Wan-Hui;Kim, Seong-Hwan
    • The Journal of the Acoustical Society of Korea
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    • v.8 no.4
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    • pp.53-59
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    • 1989
  • A new proposed method can separate heart sounds and lung sounds by the realization of adaptive noise canceler using adaptive lattice Wiener filter in contrast to adaptive transversal LMS filter and high pass filter as before. Lung sounds and ECG signal are detected for this purpose, and especially the second heart sounds are reduced by finding T wave location with a T wave seeking algorithm. As a result, for heart sounds reduction It was found that adaptive transversal LMS filter required 100-200's orders, 75-100's orders In adaptive transversal MLMS filter, and only 10-20's orders in adaptive lattice Wiener filter. Adaptive filtering technique has shown greater accuracy than high pass filtering without loss of low frequency component.

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Medical Image Restoration by Digital Image Processing (디지털영상처리를 이용한 의료영상복원)

  • Lee, Won-Seok;Chung, Kil-Soo;Lee, Yong-Gu
    • 전자공학회논문지 IE
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    • v.49 no.2
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    • pp.75-81
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    • 2012
  • In this paper, restoration methods were applied to restore analog medicine images with an aged image added and then blurred by noises. To restore the aged image blurred by the blurring function and added by noises, it was applied to the restoration methods which are inverse filtering and wiener filtering which are linear restoration techniques and Lucy-Richardson's algorithm which is nonlinear restoration technique. Moreover, ROC curve, a subjective evaluation method, was applied to evaluate the image quality of the restoration image. The wiener filtering using the ratio of constants acquired better image than the inverse filtering, but both of them couldn't improve ability to make a diagnosis. The restoration image applied to Lucy-Richardson algorithm was the best performance of the applied techniques and its sensitivity and specitivity were improved by 15[%] as much performance as the original aged image.