• Title/Summary/Keyword: Adaptive median filter

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A study on Adaptive Multi-level Median Filter using Direction Information Scales (방향성 정보 척도를 이용한 적응적 다단 메디안 필터에 관한 연구)

  • 김수겸
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.4
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    • pp.611-617
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    • 2004
  • Pixel classification is one of basic image processing issues. The general characteristics of the pixels belonging to various classes are discussed and the radical principles of pixel classification are given. At the same time. a pixel classification scheme based on image direction measure is proposed. As a typical application instance of pixel classification, an adaptive multi-level median filter is presented. An image can be classified into two types of areas by using the direction information measure, that is. smooth area and edge area. Single direction multi-level median filter is used in smooth area. and multi-direction multi-level median filter is taken in the other type of area. What's more. an adaptive mechanism is proposed to adjust the type of the filters and the size of filter window. As a result. we get a better trade-off between preserving details and noise filtering.

A Study on the Algorithm for Adaptive Odd/Even Multi-shell Median Filter (가변 문턱조건을 이용한 odd/even median filter 알고리즘)

  • 조상복;이일권
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.495-498
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    • 1999
  • In this paper, we propose the adaptive Odd/Even Multi-shell Median Filter(adaptive O/E MMF) to improve the defect that Modified Multi-shell Median Filter(MMMF) can not recover missing lines of vertical and cross direction. This filter uses odd/even multi-shells and new proposed threshold strategy The performance of the proposed filter is evaluated over image 'airfield 'by using MATLAB. As the proposed threshold strategy eliminate the number of redundant replacement, it suppresses impulse noise and recovers missing lines.

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Enhancement of noisy image sequence using order statistic-adaptive weighted average hybrid filters (순서 통계형-적응 가중평균 혼성필터를 이용한 잡음화된 영상열의 향상)

  • 박순영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.1
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    • pp.193-204
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    • 1997
  • In this research we propose the design of the Order Statistic-Adaptive Weighted Average Hybrid(OS-AWAH) filter which can suppress noise from the corrupted image sequence effectively while preserving the image structure. The proposed filter combines the desirable properties of the order static based spatial filter which can preserve the image structure while reducing noise and the adaptive weighted average based temporal filter which can adapt the filtering weights according to the amount of motion without motion estimation. Performance characteristics of the OS-AWAH filter in noisy sequences containing moving step edges are investigated throuth computer simulations and compared with the median based filters such as 3-D WM(weighted median) filter, MMF (multistage median filter), ADCWM(adaptive directional center weighted median) filter. The visual evaluations are also carried out by applyin gthe filters to the real images. The statistical analysis and experimental reslts show that the OS-AWAH filter is effective in preserving image structures while suppressing noise effectively without motion compensation preprocessing.

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Adaptive Directional Filtering Techniques for Image Sequences (동영상을 위한 적응 방향성 필터링 기술)

  • 고성제
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.7
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    • pp.922-934
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    • 1993
  • In this paper, statistical properties of the spatiotemporal center weighted median(CWM) filter for image sequences are investigated. It is statistically shown that the CWM filter preserves image structures under motion at the expense of noise suppression. To improve the CWM filter, a filter which can be effectively used in image sequence processing, the adaptive directional center weighted median filter (ADCWM), is proposed. This filter utilizes a multistage filtering structure based on adaptive symmetric order statistic(ASOS) operators which produce a pall of order statistics symmetric about the median. The ASOS's are selected by using adaptive parameters adjusted by local image statistics. It is shown experimentally that the proposed filter can preserve image structures while attenuating noise without the use of motion estimation.

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A Study on Modified Adaptive Median Filter for Impulse Noise Removal (임펄스 잡음 제거를 위한 변형된 적응 메디안 필터에 관한 연구)

  • Long, Xu;An, Young-Joo;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.05a
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    • pp.804-806
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    • 2014
  • During the transmission process of processing of image, various noises are added causing an error to the image. In order to restore these images, methods such as alpha trimmed average filter, standard median filter and switching median filter were proposed but such previous methods has insufficient noise suppression characteristics. Therefore in this paper, in order to remove the impulse noise added to the image, an adaptive median filter algorithm modified to expand the mask according to the noise density of mask pixels was proposed.

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Support Vector Machine and Improved Adaptive Median Filtering for Impulse Noise Removal from Images (영상에서 Support Vector Machine과 개선된 Adaptive Median 필터를 이용한 임펄스 잡음 제거)

  • Lee, Dae-Geun;Park, Min-Jae;Kim, Jeong-Uk;Kim, Do-Yoon;Kim, Dong-Wook;Lim, Dong-Hoon
    • The Korean Journal of Applied Statistics
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    • v.23 no.1
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    • pp.151-165
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    • 2010
  • Images are often corrupted by impulse noise due to a noise sensor or channel transmission errors. The filter based on SVM(Support Vector Machine) and the improved adaptive median filtering is proposed to preserve image details while suppressing impulse noise for image restoration. Our approach uses an SVM impulse detector to judge whether the input pixel is noise. If a pixel is detected as a noisy pixel, the improved adaptive median filter is used to replace it. To demonstrate the performance of the proposed filter, extensive simulation experiments have been conducted under both salt-and-pepper and random-valued impulse noise models to compare our method with many other well known filters in the qualitative measure and quantitative measures such as PSNR and MAE. Experimental results indicate that the proposed filter performs significantly better than many other existing filters.

A study on adaptive weighted median filter using edge information (에지정보를 이용한 적응적 가중메디안필터에 대한 연구)

  • Lee, Yong-Hwan;Park, Jang-Chun
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.10
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    • pp.2830-2837
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    • 1999
  • Image processing steps are consist of image acquisition, preprocessing, region, segmentation and recognition. But image corrupted commonly by noise reduction methods, many filters were proposed like mean filter, median filter, weighted median filter, Cheikh filter, and Kyu-cheol lee filter as spatial noise reduction filtering. We propose a new edge detection algorithm so that we find out edge existence and nonexistence. In non-edge area, we selectively apply weighted median filter based upon using information of difference value between weighted median filter's value and center pixel's value. As a result, we finally prove a better performance of noise reduction by applying adaptive weighted median filter and improvement of processing time through using simple algorithm.

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Adaptive Median Filter by Local Central Variance (로컬 중간값 분산을 이용한 적응형 메디안 필터)

  • Cho Woo-Yeon;Choi Doo-Il
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.2
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    • pp.104-115
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    • 2005
  • Median filters in the signal processing have been most widely used and have demonstrated the strongest effects. This paper proposes the adaptive median filters with noise detection. The proposed basic algorithm of the filters is to judge whether or not the noises exist on the ground of The Noise Judgment Standards. Just in case the existence of the noises is verified by the algorithm, it takes the median filter. In order to judge the existence of the noises by the algorithm, this paper introduced the noise detection method by local central variance. As a result of comparing and analyzing the features and performance of the proposed filters and the existing [5]-[10] filters on the same conditions, it was verified that the former proved to be better than the latter, Observed even by naked eyes, it was similar, too. Accordingly, it's proved that the adaptive median filters by local central variance are useful in removing the impulse noise of the median filter and reinforce the edge preservation ability.

A Study on The Modified Adaptive Median Filter Algorithm Using Odd/Even Multi-Shell (홀/짝 다중 셀을 이용한 수정된 가변 미디언 필터 알고리즘에 관한 연구)

  • Lee, Il-Gwon;Jo, Sang-Bok;Gong, Hyeong-Yun
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.38 no.4
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    • pp.401-410
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    • 2001
  • An adaptive Odd/Even Multi-shell Median Filter(Adaptive O/E MMF) is proposed by using a adaptive threshold strategy and odd/even multishells. This algorithm was verified in MATLAB and implemented on FPGA. The performance of the algorithm is evaluated by adding impulse noise and line missing into well-known images. A proposed adaptive threshold strategy may reduce the computation time and redundant arrangement. odd and even multishells can recover line missing of vertical and diagonal directions respectively Therefore, the algorithm proposed in this work can be effectively used in real time image processing applications.

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Adaptive Median Filter by Local Variance and Local Central Variance (로컬 분산과 로컬 중간값 분산을 이용한 적응형 메디안 필터)

  • 조우연;최두일
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.6
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    • pp.285-294
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    • 2004
  • Median Filters in the Signal Processing have been most widely used and have demonstrated the most strongest effects. This paper proposes the Adaptive Median Filters by using noise detection. The basic algorithm of the proposed filters is to determine whether noise or not by the each noise judgement standards, and then take the Median Filter if it satisfies the conditions as a result of judgement and returns to the original image(No Filters) if not. This paper presented Noise Detection by Local Variance and Local Central Variance for noise judgement, compared and analyzed the features and performance of existing [5]∼[10] Filters. Filter improved on the result of executing the existing filters at the same condition and showed the effects over that when it was judged with naked eyes. Accordingly, the Adaptive Median Filters by Local Variance and Local Central Variance was proven to have reinforced edge preservation ability and have the strong features for removing the Impulse Noise of the Median Filter.