• 전자공학회논문지T
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• 제36T권4호
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• pp.24-29
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• 1999

In this paper, a simple contour-preserving filtering algorithm is proposed. The goal of the contour-preserving filtering method is to remove noise ad granularity as the preprocessing for the image segmentation procedure. Our method finds edge map and separates the image into the edge region and the non-edge region using this edge map. For the non-edge region, typical smoothing filters could be used to remove the noise and the small areas during the segmentation procedure. The result of simulation shows that our method is slightly better than the typical methods such as the median filtering and gradient inverse weighted filtering in the point of view of analysis of variance (ANOVA).

• 대한전기학회논문지:시스템및제어부문D
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• 제51권10호
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• pp.468-476
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• 2002

Digital images are easily corrupted by noise during the data transmission, data capture and data processing. A technical method of noise analyzing and adaptive filtering for reducing of quantum noise in medical radio-fluoroscopy images is presented. By adjusting the characteristics of the filter according to local statistics around each pixel of the image as moving windowing, it is possible to suppress noise sufficiently while preserve edge and other significant information required in diagnosis. We proposed adaptive weighed median(AWM) filters based on local statistics. We showed two ways of realizing the AWM filters. One is a simple type of AWM filter, which is constructed by Homogeneous factor(HF). Homogeneous factor(HF) from the noise models that enables the filter to recognize the local structures of the image is introduced, and an algorithm for determining the HF fitted to the diagnostic systems with various inner statistical properties is proposed. We show by the experimented that the performances of proposed method is superior to these of other filters and models in preserving small details and suppressing the noise at homogeneous region. The proposed algorithms were implemented by Visual C++ language on a IBM-PC Pentium 550 for testing purposes and the effects and results of the filter in the various levels of noise and images were proposed by comparing the values of NMSE(normalized mean square error) with the value of the other existing filtering methods.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.981-984
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• 2005

현재, 영상처리에 있어서 잡음을 제거함과 동시에 영상의 에지성분을 보존하는 필터링 방법에 대한 연구가 활발히 진행되고 있다. 그리고 임펄스 노이즈 환경에서는 SM(standard median) 필터가우수한 잡음 제거 성능을 나타내었으나, 영상의 에지성분에 대한 오류가 발생하고 있다. 이에 따라, SM 필터를 개선한 다양한 방법들이 제안되었으며, CWM(center weighted median) 필터가 대표적이다. 또한, 에지의 보존이나 처리속도의 관점에서 더욱 향상된 성능을 나타내기 위한 방법으로 min-max 연산에 기반한 방법들이 있다 본 논문에서는 임펄스 노이즈에 의해 훼손된 화소에 대해, 그 화소를 둘러 싼 surrounding band의 최대 또는 최소 값을 이용하여 처리하였으며, 시뮬레이션을 통해 제안한 필터의 성능을 기존의 방법과 비교하였다.

• 방송공학회논문지
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• 제8권3호
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• pp.288-296
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• 2003

ATSC (Advanced Television System Committee)에서는 18가지의 DTV (Digital Television)를 위한 동영상 포맷들을 제정하였다. ATSC 포맷들은 스캔 포맷, 크기 포맷, 프레임율 포맷 등의 적당한 조합들이다. 효과적인 MPEG-2 트랜스코딩을 위해서는 이런 포맷들 간의 변환도 지원할 수 있어야 한다. 여러 포맷 변환들 중에서 특히 스캔 포맷 변환은 프레임율과 크기 변화가 함께 일어나기 때문에 상대적으로 구현하기가 힘들다. 스캔포맷 변환으로 픽쳐 타입도 함께 변하기 때문에 트랜스코더의 움직임 추정부 (motion estimation; ME)에 상당한 연산량 부담을 주게 된다. 이런 문제를 해결하기 위해 본 논문은 스캔포맷 변환을 지원하는 MPEG-2 동영상 트랜스코딩을 위한 고속 움직임 추정 알고리즘을 제안한다. 먼저, 트랜스코더의 수신단은 입력 비트열로부터 재 부호화(re-encoding)에 적합한 후보 움직임 벡터들을 추출한다. 그런 다음. 가중치 중간값 선택기(weighted median selector)를 이용하여, 여러 후보 움직임 벡터들 중에서 최적의 움직임 벡터를 선택한다. 모의 실험 결과는 제안한 움직임 추정 알고리즘이 전역 탐색 기법(Full Search Algorithm: FSA)에 비해 현저하게 적은 연산량을 가지면서, FSA와 거의 동일한 PSNR 성능을 가짐을 증명한다.

• Communications for Statistical Applications and Methods
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• 제11권1호
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• pp.153-160
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• 2004

In recent years, the size of data set which we usually handle is enormous, so a lot of outliers could be included in data set. Therefore the robust procedures that automatically handle outliers become very importance issue. We consider the robust estimation problem of location parameter in the univariate case. In this paper, we propose a new method for defining robustness weights for the weighted mean based on the median distance of observations and compare its performance with several existing robust estimators by a simulation study. It turns out that the proposed method is very competitive.

• 전자공학회논문지S
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• 제35S권1호
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• pp.141-148
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• 1998

We propose an efficient method of de-interlacing in the post-pocessing of HDTV signal. Since the proposed method considers human visual weight, it gives the better performance in the edge information preservation than that of the median filter. The processing time of the proposed method is twice faster than median filter, therefore the proposed method is suitable for the real-time de-interlacing in the post-processing of HDTV signal.

• 대한안전경영과학회지
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• 제3권3호
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• pp.175-190
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• 2001

We propose, a new process capability index $C_{psk}$(WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distributions from its mean to create two new distributions which have the same mean but different standard deviations. In this paper we propose an example, a distributions generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods in terms of sensitivity to departure to the process mean/median from the target value for non-normal processes. Second method show using the percentage nonconforming by the Pearson, Johnson and Burr systems. This example shows a little difference between the Pearson system and Burr system, but Johnson system underestimated than the two systems for process capability.

• Wind and Structures
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• 제26권6호
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• pp.383-395
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• 2018

An accurate determination of wind speed distribution is the basis for an evaluation of the wind energy potential required to design a wind turbine, so it is important to estimate unknown parameters of wind speed distribution. In this paper, Gumbel distribution is used in modelling wind speed data, and alternative robust estimation methods to estimate its parameters are considered. The methodologies used to obtain the estimators of the parameters are least absolute deviation, weighted least absolute deviation, median/MAD and least median of squares. The performances of the estimators are compared with traditional estimation methods (i.e., maximum likelihood and least squares) according to bias, mean square deviation and total mean square deviation criteria using a Monte-Carlo simulation study for the data with and without outliers. The simulation results show that least median of squares and median/MAD estimators are more efficient than others for data with outliers in many cases. However, median/MAD estimator is not consistent for location parameter of Gumbel distribution in all cases. In real data application, it is firstly demonstrated that Gumbel distribution fits the daily mean wind speed data well and is also better one to model the data than Weibull distribution with respect to the root mean square error and coefficient of determination criteria. Next, the wind data modified by outliers is analysed to show the performance of the proposed estimators by using numerical and graphical methods.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.883-885
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• 2013

영상복원은 영상에 첨가되는 여러가지 잡음을 제거하여 잡음이 영상에 미치는 영향을 줄이는 것이다. 영상복원을 위해, 평균 필터, 메디안 필터, 가중치 필터 등 방법들이 제안되었으나 이러한 기존의 방법들은 잡음제거 및 에지 보존 성능이 미흡하다. 따라서 본 논문에서는 효과적으로 잡음을 제거하기 위해 마스크 메디안 값의 여부에 따라 마스크 크기를 확대 시키는 변형된 적응 메디안 필터 알고리즘을 제안하였다. 그리고 시뮬레이션을 통해 기존의 방법들과 비교하였으며 판단의 기준으로 MSE(mean squared error)를 사용하였다.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.308-318
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• 2022

Noise is a serious issue. While sending images via electronic communication, Impulse noise, which is created by unsteady voltage, is one of the most common noises in digital communication. During the acquisition process, pictures were collected. It is possible to obtain accurate diagnosis images by removing these noises without affecting the edges and tiny features. The New Average High Noise Density Median Filter. (HNDMF) was proposed in this paper, and it operates in two steps for each pixel. Filter can decide whether the test pixels is degraded by SPN. In the first stage, a detector identifies corrupted pixels, in the second stage, an algorithm replaced by noise free processed pixel, the New average suggested Filter produced for this window. The paper examines the performance of Gaussian Filter (GF), Adaptive Median Filter (AMF), and PHDNF. In this paper the comparison of known image denoising is discussed and a new decision based weighted median filter used to remove impulse noise. Using Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), and Structure Similarity Index Method (SSIM) metrics, the paper examines the performance of Gaussian Filter (GF), Adaptive Median Filter (AMF), and PHDNF. A detailed simulation process is performed to ensure the betterment of the presented model on the Mini-MIAS dataset. The obtained experimental values stated that the HNDMF model has reached to a better performance with the maximum picture quality. images affected by various amounts of pretend salt and paper noise, as well as speckle noise, are calculated and provided as experimental results. According to quality metrics, the HNDMF Method produces a superior result than the existing filter method. Accurately detect and replace salt and pepper noise pixel values with mean and median value in images. The proposed method is to improve the median filter with a significant change.