• Title/Summary/Keyword: Weighted filter

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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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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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A study on improvement of the weighted median filter in low noise (저잡음하에서 WM 필터의 개선에 관한 연구)

  • 이용환;서민형;우상근;박장춘
    • Proceedings of the Korean Information Science Society Conference
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    • 1998.10c
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    • pp.467-468
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    • 1998
  • Impulsive noise appears as black and/or white spots in an image. It is usually caused by errors during the image acquisition or transmission through communication channels. This paper presents a study on the impulsive noise reduction filter of digital image. A much more effective method for removing impulse noise is weighted median filtering. But it loses some information by changing center value with no condition. We propose some new technique to change center value with some conditions. In this paper, the performance of conditional weighted median filter is compared to the commonly used median filter, mean filter, max/min filter, and weighted median filter. A quantitative comparison is performed on MSE (Mean Square Error), RMSE (Root Mean Square Error), and SNR (Signal to Noise Ratio). Proposed conditional weighted median filter can yield better performance than regular filters.

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A Study on the Hardware Implementation of A 3${\times}$3 Window Weighted Median Filter Using Bit-Level Sorting Algorithm (비트 레벨 정렬 알고리즘을 이용한 3${\times}$3 윈도우 가중 메디언 필터의 하드웨어 구현에 관한 연구)

  • 이태욱;조상복
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.3
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    • pp.197-205
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    • 2004
  • In this paper, we studied on the hardware implementation of a 3${\times}$3 window weighted median filter using bit-level sorting algorithm. The weighted median filter is a generalization of the median filter that is able to preserve :,harp changes in signal and is very effective in removing impulse noise. It has been successfully applied in various areas such as digital signal and video/image processing. The weighted median filters are, for the most part, based on word-level sorting methods, which have more hardware and time complexity, However, the proposed bit-serial sorting algorithm uses weighted adder tree to overcome those disadvantages. It also offers a simple pipelined filter architecture that is highly regular with repeated modules and is very suitable for weighted median filtering. The algorithm was implemented by VHDL and graphical environment in MAX+PlusII of ALTERA. The simulation results indicate that the proposed design method is more efficient than the traditional ones.

Mixed Weighted Filter for Removing Gaussian and Impulse Noise

  • Yinyu, Gao;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2011.10a
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    • pp.379-381
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    • 2011
  • The image signal is often affected by the existence of noise, noise can occur during image capture, transmission or processing phases. noises caused the degradation phenomenon and demage the original signal information. Many studies are being accomplished to restore those signals which corrupted by mixed noise. In this paper, we proposed mixed weighted filter for removing Gaussian and impulse noise. we first charge the noise type, then, Gaussian is removed by a weighted mean filter and impulse noise is removed by self-adaptive weighted median filter that can not only remove mixed noise but also preserve the details. And through the simulation, we compared with the conventional algorithms and indicated that proposed method significant improvement over many other existing algorithms and can preserve image details efficiently.

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Image Deblocking Scheme for JPEG Compressed Images Using an Adaptive-Weighted Bilateral Filter

  • Wang, Liping;Wang, Chengyou;Huang, Wei;Zhou, Xiao
    • Journal of Information Processing Systems
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    • v.12 no.4
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    • pp.631-643
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    • 2016
  • Due to the block-based discrete cosine transform (BDCT), JPEG compressed images usually exhibit blocking artifacts. When the bit rates are very low, blocking artifacts will seriously affect the image's visual quality. A bilateral filter has the features for edge-preserving when it smooths images, so we propose an adaptive-weighted bilateral filter based on the features. In this paper, an image-deblocking scheme using this kind of adaptive-weighted bilateral filter is proposed to remove and reduce blocking artifacts. Two parameters of the proposed adaptive-weighted bilateral filter are adaptive-weighted so that it can avoid over-blurring unsmooth regions while eliminating blocking artifacts in smooth regions. This is achieved in two aspects: by using local entropy to control the level of filtering of each single pixel point within the image, and by using an improved blind image quality assessment (BIQA) to control the strength of filtering different images whose blocking artifacts are different. It is proved by our experimental results that our proposed image-deblocking scheme provides good performance on eliminating blocking artifacts and can avoid the over-blurring of unsmooth regions.

A Study on Modified Spatial Weighted Filter in Mixed Noise Environments (복합잡음 환경에서 변형된 공간 가중치 필터에 관한 연구)

  • Kwon, Se-Ik;Kim, Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.1
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    • pp.237-243
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    • 2015
  • In recent image processing, active researches have been made along with rapid development in digital times. However, it is know that the image degradation occurs due to various external factors in the processes of image data processing, transmission and storage, and the main reason of image degradation is due to the noise. Typical methods to remove the noise are CWMF(center weighted median filter), A-TMF(alpha-trimmed mean filter) and AWMF(adaptive weighted median filter) and these methods have a little bit lacking noise reduction characteristics in mixed noise environments. Therefore, in order to remove the mixed noise, image restoration filter processing algorithm was suggested in this paper which processes by applying the median value of the mask and space weighted value after noise judgment. And for the objective judgment, it was compared with existing methods and PSNR(peak signal to noise ratio) was used as a judgment standard.

A Study of PPG Wave and Pulse Measurement on Radial Artery Using Digital Potentiometer and Exponentially Weighted Moving Average Filter (디지털 가변저항과 지수가중 이동평균필터를 통한 요골동맥에서의 PPG 파형과 맥박 측정에 관한 연구)

  • Jung, In-Bok;Kim, Kyung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.7
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    • pp.962-967
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    • 2014
  • In this paper, through a digital potentiometer and exponentially weighted moving average filter, pulse and PPG waveform measurable device was fabricated in radial artery. If this device is not proper about signal size in analog part, MCU can judge easily by adjusted amplification through digital potentiometer, using exponentially weighted moving average filter is able to filter out more clear value of ADC. I presumed pulse rate as value of measuring time between point of maximum contraction from sensing signal in radial artery of wrist. Therefore, this means can measure stable pulse rate and PPG waveform, finger as well as radial artery, whether signal size of each person is different finger as well as radial artery.

An Improved Weighted Filter for AWGN Removal (AWGN 제거를 위한 개선된 가중치 필터)

  • Long, Xu;Kim, Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.5
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    • pp.1227-1232
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    • 2013
  • Recently, the expectation of quality about images over the increasing demand of digital devices is increasing with the development of the technology of the digital. But the images are degraded by a variety of causes, and the main reason is the noises. Therefore, the necessity of denoising comes to the fore, and the research for denoising is progressing dynamically. The images are mainly degraded by AWGN(additive white Gaussian noise), and the characteristics of denoising of existing methods such as mean filter are insufficient. In this paper, an algorithm combined by the spatial weighted filter and the modified adaptive weighted filter is proposed in order to effectively remove the AWGN. In the simulation result, the proposed algorithm showed excellent denoising capabilities.

Modified Median Filter for Image Restoration in Salt and Pepper Noise Environments (Salt and Pepper 잡음 환경에서 영상 복원을 위한 변형된 메디안 필터)

  • Hong, Sang-Woo;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.252-255
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    • 2014
  • Image treatment is becoming mainstream as the demand for image restoration has drastically increased in the digital era. But in the process of acquiring, transmitting and treating video data, the salt and pepper noise damages the image. One of the major methods used for restoring images are SMF(standard median filter), CWMF(center weighted median filter) and SWMF(switching weighted median filter), but these filters all leave a bit to be desired in terms of removing noise and preserving edge. Therefore, a transformed median filter is suggested through the algorithm presented for the restoration of damaged images.

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