• Korean Journal of Optics and Photonics
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• v.21 no.1
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• pp.21-25
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• 2010

In this paper, in order to enhance the image reconstruction performance of white light scanning interferometry(WLI), we demonstrate the scattered point noise filtering performance of post-processing methods. Median filtering is similar to using an averaging filter. Because the median value is less sensitive than the mean to extreme values, the median filter can remove the scattered point noise from a height-map without significantly reducing the sharpness of the image. In several specific cases, however, the median filter can't remove the scattered point noise. Therefore, we propose a comparative mean filter that uses order-statistic filtering and the mean of the neighborhood pixels. The performance is demonstrated by measuring an array of metal solder balls fabricated on PCB. The proposed method reduced the noise pixels by 4.4 percent.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.167-170
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• 2005

Recently, filtering methods for attenuating noise while preserving image details are in progress actively. And SM(standard median) filter showed a great performance for noise removal in impulse noise environment but, it caused edge cancellation error. So, variable methods that modified SM(standard median) filter have been proposed, and CWM(center weighted median) filter is representative. Also, there are several methods to improve the efficiency based on min/max operation in term of preserving detail and filtering speed. In this paper, we managed a pixel corrupted by impulsive noise using min/max value of the surrounding band enclosing a pixel, and compared the efficiency with exiting methods in the simulation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.4
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• pp.77-77
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• 2001

MMMF(Modified 2D Multi-shell Median Filter)를 기초로 하여 가변 문턱 조건과 홀/짝수 다중셀을 이용한 Adaptive Odd/Even MMF(Multi-shell Median Filter)를 제안하였다. 제안된 알고리즘은 MATLAB을 이용하여 연구하고 테스트하였다. 제안된 알고리즘의 성능은 이미 잘 알려진 이미지에 임펄스 노이즈(Impulse Noise)와 Line Missing을 적용하여 평가하였고 이를 FPGA로 구현하였다. 제안된 가변 문턱 조건은 연산 시간과 불필요한 재배치를 줄였고, 홀수 셀과 짝수 셀은 각각 십자 방향과 대각선 방향의 Line Missing을 복구하였다. 특히 짧은 연산 시간으로 실시간을 요구하는 이미지 처리 분야에서 효과적으로 이용할 수 있다.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.153-158
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• 2008

Blocking artefact noise is necessarily happened in compressed images using block-coded algorithms such as JPEC compressing algorithm. This noise is more recognizable especially in highly compressed images. In this paper, an algorithm is presented for reduction of blocking artefact noise using wavelet. Furthermore, we also mention about the median filter which is often used in image processing. Moreover, we compared the algorithm in this paper with the median filter, and its result was much better than the median filter both visually and numerically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2701-2706
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• 2009

There are Impulse noise and AWGN in a general image processing. Various methods have been proposed to remove these noises. Well-known filters are Mean, Min-max and Median filter and these show different characteristics depending on the noises. When Impulse noise and AWGN are in superposition environment, single filter doesn't remove noises well. Therefore in this paper, we suggested a switching filter using a probability of noise to restore images in this environment. And we compared a filter with conventional method through simulations.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2197-2204
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• 2015

In recent years, medical image diagnosis has growing significant momentous in the medicinal field. Brain and lung image of patient are distorted with salt and pepper noise is caused by moving the head and chest during scanning process of patients. Reconstruction of these images is a most significant field of diagnostic evaluation and is produced clearly through techniques such as linear or non-linear filtering. However, restored images are produced with smaller amount of noise reduction in the presence of huge magnitude of salt and pepper noises. To eliminate the high density of salt and pepper noises from the reproduction of images, a new efficient fuzzy based median filtering algorithm with a moderate elapsed time is proposed in this paper. Reproduction image results show enhanced performance for the proposed algorithm over other available noise reduction filtering techniques in terms of peak signal -to -noise ratio (PSNR), mean square error (MSE), root mean square error (RMSE), mean absolute error (MAE), image enhancement factor (IMF) and structural similarity (SSIM) value when tested on different medical images like magnetic resonance imaging (MRI) and computer tomography (CT) scan brain image and CT scan lung image. The introduced algorithm is switching filter that recognize the noise pixels and then corrects them by using median filter with fuzzy two-sided π- membership function for extracting the local information.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.255-259
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• 2003

The noise canceling on gray image morphing with median filter is presented. The processing is that interpolate the image with B-spline, specify the distinctive points, cancel the noise by median filtering and perform the morphing. The experiment results denoise the blocking degradation as 20%, correct and present a soft morphing image processing.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1085-1093
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• 2010

This paper proposes a multiple filter for reduction of received signal fluctuation and enhancement of step altitude edge detection in FMCW radar altimeter. The proposed filter was composed of alpha-trimmed mean filter, frequency variation limiter, and 1/3 order static filter. Simulations by analysis of received signal show that the proposed filter provides better performance than moving average and standard median filters with error reduction. In particular, the proposed filter was improved in the ability of reducing fluctuation for ground hovering.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.31-39
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• 2010

The paper proposes the median filter based Retinex algorithm to detect the lanes in a foggy image. Whether an input image is foggy or not is determined by analyzing the histogram in the pre-defined ROI(Region of Interest). If the image is determined as a foggy one, then it is improved by the median filter based Retinex algorithm. By replacing the Gaussian filter by the median filter in the Retinex algorithm, the processing time can be reduced and the lane features can be detected more robustly. Once the enhanced image is acquired, the binarization based on multi-threshold and the labeling operations are applied. Finally, it detects the lane information using the size and direction parameters of the detected lane features. The proposed algorithm has been evaluated by using various foggy images collected on different road conditions to prove that it detects lanes more robustly in most cases than the conventional methods.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.21-28
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• 2021

Computed tomography (CT) has the problem of having more radiation exposure compared to other radiographic apparatus. There is a low-dose imaging technique for reducing exposure, but it has a disadvantage of increasing noise in the image. To compensate for this, various noise reduction algorithms have been developed that improve image quality while reducing the exposure dose of patients, of which the median modified Wiener filter (MMWF) algorithm that can be effectively applied to CT devices with excellent time resolution has been presented. The purpose of this study is to optimize the mask size of MMWF algorithm and to see the excellence of noise reduction of MMWF algorithm for existing algorithms. After applying the MMWF algorithm with each mask sizes set from the MASH phantom abdominal images acquired using the MATLAB program, which includes Gaussian noise added, and compared the values of root mean square error (RMSE), peak signal-to-noise ratio (PSNR), coefficient correlation (CC), and universal image quality index (UQI). The results showed that RMSE value was the lowest and PSNR, CC and UQI values were the highest in the 5 x 5 mask size. In addition, comparing Gaussian filter, median filter, Wiener filter, and MMWF with RMSE, PSNR, CC, and UQI by applying the optimized mask size. As a result, the most improved RMSE, PSNR, CC, and UQI values were showed in MMWF algorithms.