• Title/Summary/Keyword: Median filtering

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SNR and PSNR measurements and analysis of median filtering for the removal of impulse noise from CR imaging

  • Hong, Seong-Il;Dong, Kyung-Rae;Ryu, Young-Hwan
    • International Journal of Contents
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    • v.5 no.4
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    • pp.7-12
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    • 2009
  • In this paper, the authors showed that the removal of impulse noise in CR images was implemented using variety of median filters and SNR/PSNR measurements. They used three kinds of medical images-hand, skull, and knee- for experimental results. But the noise in CR image was only the impulse noise. In real medical image, the noise of an image would be very different type. Therefore. the lack of experimental results using different noise in CR images is one flaw.

Comparison of Filter Selection for Compressed Sensing (압축센싱을 위한 필터선택 비교)

  • Pham, Phuong Minh;Shim, Hiuk Jae;Jeon, Byeungwoo
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2012.11a
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    • pp.188-190
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    • 2012
  • Compressed Sensing (CS) has been developed for several years. Among many CS algorithms for image, the Block-based Compressed Sensing with Smoothed Projected Landweber (BCS-SPL) demonstrates its excellent performance in low-complexity and near-optimal reconstruction. Several noise filtering algorithms of image reconstruction have been introduced such as the Wiener or the median filters, etc. In general, each filter has its own advantages and disadvantages depending on specific coding scheme. In this paper, we show that reconstruction performance can be varied according to the choice of filter. When a sub-rate value is changed, different filter causes different effect as well. Concerning the sub-rate, an inner filter can be chosen to improve the reconstructed image quality.

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Transfer Function Estimation Using a modified Wavelet shrinkage (수정된 웨이블렛 축소 기법을 이용한 전달함수의 추정)

  • 김윤영;홍진철;이남용
    • Journal of KSNVE
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    • v.10 no.5
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    • pp.769-774
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    • 2000
  • The purpose of the work is to present successful applications of a modified wavelet shrinkage method for the accurate and fast estimation of a transfer function. Although the experimental process of determining a transfer function introduces not only Gaussian but also non-Gaussian noises, most existing estimation methods are based only on a Gaussian noise model. To overcome this limitation, we propose to employ a modified wavelet shrinkage method in which L1 -based median filtering and L2 -based wavelet shrinkage are applied repeatedly. The underlying theory behind this approach is briefly explained and the superior performance of this modified wavelet shrinkage technique is demonstrated by a numerical example.

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A New Algorithm for Ghost Cancellation System (새로운 고스트 제거 알고리즘)

  • Park, Kyung-Bae;Hwang, Hu-Mor
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.904-906
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    • 1995
  • Based on the detection of the size of datas of multipath channel characterization, we propose a new algorithm. called the impulse size based adaptive median filter(ISMF), for ghost cancellation system. The ISMF consists of two levels. The first one is the impulse noise size detection level and the second one is the adaptive median filtering level to remove the impulse noise detected. Test results confirm that the proposed ISMF removes impulse noise due to multipath channel characterization while preserving signal as well as ghosts so that the LMS algorithm performs effectively.

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Implementation of Image Enhancement Filter System Using Genetic Algorithm (유전자 알고리즘을 이용한 영상개선 필터 시스템 구현)

  • Gu, Ji-Hun;Dong, Seong-Su;Lee, Jong-Ho
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.51 no.8
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    • pp.360-367
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    • 2002
  • In this paper, genetic algorithm based adaptive image enhancement filtering scheme is proposed and Implemented on FPGA board. Conventional filtering methods require a priori noise information for image enhancement. In general, if a priori information of noise is not available, heuristic intuition or time consuming recursive calculations are required for image enhancement. Contrary to the conventional filtering methods, the proposed filter system can find optimal combination of filters as well as their sequent order and parameter values adaptively to unknown noise types using structured genetic algorithms. The proposed image enhancement filter system is mainly composed of two blocks. The first block consists of genetic algorithm part and fitness evaluation part. And the second block consists of four types of filters. The first block (genetic algorithms and fitness evaluation blocks) is implemented on host computer using C code, and the second block is implemented on re-configurabe FPGA board. For gray scale control, smoothing and deblurring, four types of filters(median filter, histogram equalization filter, local enhancement filter, and 2D FIR filter) are implemented on FPGA. For evaluation, three types of noises are used and experimental results show that the Proposed scheme can generate optimal set of filters adaptively without a pioi noise information.

Non-Impulse Noise Reduction of Binary Image based on Morphological Arithmetic (형태학적 연산에 기반한 이진영상의 비임펄스 잡음제거)

  • 김재석;정성옥
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.6
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    • pp.909-914
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    • 2002
  • In this thesis, noise reduction of image with impulse noise in circle image removed noise to harness existing median filter for noise reduction from image data of damage by noise when impulse noise is high or noise reduction is low, but it is not made up of noise reduction to harness existing median filter in case of existence of non-impulse noise. Therefore noise reduction of image with non-impulse noise had to remove noise by morphological arithmetic in this thesis's proposition. In contrast to median filtering, result of edge detection is more efficient after remove non-impulse noise by method of thesis's proposition and it compare and demonstrate through this experimentation.

Color Image Filter Using Fuzzy Logic (퍼지 논리를 이용한 컬러 영상 필터)

  • Ko, Chang-Ryong;Koo, Kyung-Wan;Kim, Kwang-Baek
    • Journal of the Korea Society of Computer and Information
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    • v.16 no.12
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    • pp.43-48
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    • 2011
  • Among various methods proposed earlier, fuzzy image filtering is usually one of the favored techniques because it has less blurring effect and the decrease of noise removal rate after filtering. However, fuzzy filtering is ineffective on color images since it is firstly developed with gray scale. Thus, in this paper, we propose a fuzzy filtering algorithm for color images. First, we divide RGB color information from image into three channels of R, G, and B and judge the possibility of each pixel with mask by fuzzy logic independently. The output pixel value might be the average or median according to the degree of noise. Our experiment successfully verifies the effectiveness of new algorithm in color image.

An Impulse Noise-Robust Wiener Filter

  • Park, Soon-Young
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1992.06a
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    • pp.33-36
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    • 1992
  • In this paper we propose the impulse noise-robust Wiener filter based on a combination of Wiener and modified trimmed mean(MTM) filters. The robust Wiener filter uses the trimming operation of the MTM filter to replace the outliers with the median within the window and the new set of samples which can be considered as the random process with same mean are inputted into the following Wiener filter. We show that the robust Wiener filter is effective in frequency selective filtering of nonstationary signals while preserving signal edges with the rejection of impulse noise.

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A Study on Automatic Generation of the Image-Based Environment using Median Vector Filtering (기준 특징 벡터 필터링을 이용한 영상기반 환경의 생성에 관한 연구)

  • 김정훈;윤용인;최종수;김태은
    • Proceedings of the Korea Multimedia Society Conference
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    • 2001.06a
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    • pp.99-102
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    • 2001
  • 컴퓨터 기술의 향상과 인터넷의 보급화로 인하여 가상환경의 구현에 대한 관심도 높아지고 있으며 이에 따른 여러 기술들이 제안되고 있다. 본 논문은 간단한 영상취득장치로 얻은 몇 장의 영상으로 영상 기반 환경을 자동으로 생성하는 방법에 대해 논한다. 특히, 취득한 영상간의 카메라 회전 성분에 강건한 기준 특징 벡터 필터링 방법을 제안하며 실험을 통해 그 유용성을 검증한다.

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A Blind Watermarking Technique Using Difference of Approximation Coefficients in Wavelet Domain (웨이블릿 영역에서 근사 계수의 증감 정보를 이용한 블라인드 워터마크)

  • 윤혜진;성영경;최태선
    • Proceedings of the IEEK Conference
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    • 2002.06d
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    • pp.219-222
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    • 2002
  • In this paper, we propose a new blind image watermarking method in wavelet domain. It is necessary to find out watermark insertion location in blind watermark. We use horizontal and vertical difference of LL components to select watermark insertion location, because increment or decrement of successive components is rarely changed in LL band. A pseudo-random sequence is used as a watermark. Experimental results show that the proposed method is robust to various kinds of attacks such as JPEG lossy compression, averaging, median filtering, resizing, histogram equalization, and additive Gaussian noise.

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