• 제목, 요약, 키워드: Discrete stationary wavelet transform

검색결과 26건 처리시간 0.046초

SWT -based Wavelet Filter Application for De-noising of Remotely Sensed Imageries

  • Yoo Hee-Young;Lee Kiwon;Kwon Byung-Doo
    • 대한원격탐사학회:학술대회논문집
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    • pp.505-508
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    • 2005
  • Wavelet scheme can be applied to the various remote sensing problems: conventional multi-resolution image analysis, compression of large image sets, fusion of heterogeneous sensor image and segmentation of features. In this study, we attempted wavelet-based filtering and its analysis. Traditionally, statistical methods and adaptive filter are used to manipulate noises in the image processing procedure. While we tried to filter random noise from optical image and radar image using Discrete Wavelet Transform (DW1) and Stationary Wavelet Transform (SW1) and compared with existing methods such as median filter and adaptive filter. In result, SWT preserved boundaries and reduced noises most effectively. If appropriate thresholds are used, wavelet filtering will be applied to detect road boundaries, buildings, cars and other complex features from high-resolution imagery in an urban environment as well as noise filtering

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SWT (Stationary Wavelet Transform)을 이용한 영상 잡음 제거

  • 유혜림;조현숙;이형;이인정
    • 한국정보기술응용학회:학술대회논문집
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    • pp.9-28
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    • 2007
  • It is well known that wavelet transform is a signal processing technique which can display the signals on in both time and frequency domain. In this paper, we proposed a new approach based on stationary wavelet transform to provide an enhanced approach for eliminating noise. A 'stationary wavelet transform', where the coefficient sequences are not decimated at each stage, is described. The testing result on sample iris images has shown an enhanced image quality and also show that it has a superior performance than traditional discrete wavelet transform.

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Daubechies 정상 웨이블릿을 이용한 무인항공기 촬영 영상 성능 개선 (Performance Improvement of Aerial Images Taken by UAV Using Daubechies Stationary Wavelet)

  • 김성훈;홍교영
    • 한국항행학회논문지
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    • v.20 no.6
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    • pp.539-543
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    • 2016
  • 본 논문은 Daubechies 정상 웨이블릿 변환을 이용하여 무인항공기 항공촬영 영상의 성능을 향상하기 위한 기법에 대해 연구하였다. 무인항공기에서 획득된 영상이 가장 일반적이고 보편적으로 적용되는 가우시안 잡음에 의하여 손상되었을 경우, 영상의 성능을 개선하기 위한 실험을 수행하였다. 정상 웨이블릿 변환은 DWT (discrete wavlet transform)에서 다운샘플링에 의해 발생하는 문제점을 해결하기 위한 변환방법으로써 잡음제거에 DWT보다 효과적이라고 알려져 있다. 또한 Haar 웨이블릿은 불연속 함수인 이유로 매끄러운 신호나 영상처리에 효과적이지 못하다. 이에 본 연구에서는 daubechies 정상 웨이블릿을 이용하여 잡음을 제거하였으며 기존 haar 정상 웨이블릿을 적용하였을 때 보다 더 성능이 개선됨을 확인하였다.

Undecimated 웨이블릿 변환응용 (An Application of the Undecimated Discrete Wavelet Transform)

  • Lee, Chang-Soo;Yoo, Kyung-Yul
    • 대한전자공학회:학술대회논문집
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    • pp.605-608
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    • 2000
  • This paper introduces a new structure for the undecimated discrete wavelet transform (UDWT). This structure combines the stationary wavelet transform with a lifting scheme and its design is based on a polyphase structure .where the downsampling and split stage are removed. The suggested structure inherits the simplicity of the lifting scheme, such that the inverse transform is easily implemented. The performanace of the proposed undecimated lifting is verified on a signal denoising application.

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2-D 웨이브릿 변환을 이용한 해양 탄성파탐사 자료의 잡음 감쇠 (Noise Attenuation of Marine Seismic Data with a 2-D Wavelet Transform)

  • 김진후;김성보;김현도;김찬수
    • 한국마린엔지니어링학회지
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    • v.32 no.8
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    • pp.1309-1314
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    • 2008
  • Seismic data is often contaminated with high-energy, spatially aliased noise, which has proven impractical to attenuate using Fourier techniques. Wavelet filtering, however, has proven capable of attacking several types of localized noise simultaneously regardless of their frequencies. In this study a 2-D stationary wavelet transform is used to decompose seismic data into its wavelet components. A threshold is applied to these coefficients to attenuate high amplitude noise, followed by an inverse transform to reconstruct the seismic trace. The stationary wavelet transform minimizes the phase-shift errors induced by thresholding that occur when the conventional discrete wavelet transform is used.

Q인자 조절 가능 2차원 이산 웨이브렛 변환 필터의 설계와 성능분석 (Tunable Q-factor 2-D Discrete Wavelet Transformation Filter Design And Performance Analysis)

  • 신종홍
    • 디지털산업정보학회논문지
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    • v.11 no.1
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    • pp.171-182
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    • 2015
  • The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

노이지 제거기법을 이용한 지중송전계통 고장점 추정 (Fault Location Using Noise Cancellation Technique on Underground Power Cable Systems)

  • 정채균;이종범
    • 대한전기학회:학술대회논문집
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    • pp.440-441
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    • 2006
  • The fault location algorithm based on wavelet transform was developed to locate the fault more accuracy after the operation of relay. The stationary wavelet transform(SWT) was introduced instead of conventional discrete wavelet transform(DWT) because SWT has redundancy properties which is more useful in noise signal processing. The algorithm was based on the correlation of wavelet coefficients at multi-scales. Fault location algorithm was tested by simulation on real power cable system. From these results, the fault can be located even in very difficult situations, such as at different inception angle and fault resistance.

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웨이브렛 변환을 이용한 전자빔 용접 진단 (Electron Beam Welding Diagnosis Using Wavelet Transform)

  • 윤충섭
    • Journal of Welding and Joining
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    • v.21 no.6
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    • pp.33-39
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    • 2003
  • Wavelet transform analysis results show a spectrum energy distribution of CWT along scale factors distinguish the partial, full and over penetration in a electron beam welding by analyzing the curve of spectrum energy at small scale, middle and large scale range, respectively. Two types of signals collected by Ion collector and x-ray sensors and analyzed. The acquired signals from sensors are very complicated since these signals are very closely related the dynamics of keyhole which interact the very high density energy with materials during welding. The results show the wavelet transform is more effective to diagnosis than Fourier Transform, further for the general welding defects which are not a periodic based, but a transient, non-stationary and time-varying phenomena.

정상 웨이블렛 변환을 이용한 로버스트 영상 융합 (Robust Image Fusion Using Stationary Wavelet Transform)

  • 김희훈;강승효;박재현;하현호;임진수;임동훈
    • 응용통계연구
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    • v.24 no.6
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    • pp.1181-1196
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    • 2011
  • 영상 융합은 특징이 다른 두 개 이상의 영상에 대하여 각 영상의 특징을 모두 갖는 하나의 영상으로 재구성하는 기술로 의료 분야, 군사 분야, 원격 탐사 분야 등 여러 분야에 활용되고 있다. 지금까지 웨이블렛 기반 영상 융합은 주로 이산 웨이블렛 변환 하에서 고주파 영역에서는 표준편차와 같은 액티비티(activity) 측도를 사용하고 저주파 영역에서는 두 영상의 픽셀값의 평균을 취함으로써 이루어져 왔다. 그러나, 이산 웨이블렛 변환은 이동불변(translation-invariance)하지 않으므로 융합 영상에 블록 인공물이 생기곤 한다. 본 논문에서는 이산 웨이블렛 변환의 단점을 보완한 정상 웨이블렛 변환을 이용하여 고주파 영역에서는 영상 특징에 민감하지 않은 사분위수 범위를 사용하고 저주파 영역에서는 고주파 영역의 사분위수 범위 정보를 이용하여 영상을 융합하고자 한다. 영상 실험 결과, 제안된 방법은 정성적이고 정량적인 평가에서 입력 영상의 종류에 관계없이 로버스트한 결과를 낳음을 알 수 있었다.

SWT와 진행파를 이용한 지중송전계통 고장점 추정 기법 개발 (Development of Fault Location Method Using SWT and Travelling Wave on Underground Power Cable Systems)

  • 정채균;이종범
    • 전기학회논문지
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    • v.57 no.2
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    • pp.184-190
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    • 2008
  • The fault location algorithm based on stationary wavelet transform was developed to locate the fault point more accurately. The stationary wavelet transform(SWT) was introduced instead of conventional discrete wavelet transform(DWT) because SWT has redundancy properties which is more useful in noise signal processing. In previous paper, noise cancellation technique based on the correlation of wavelet coefficients at multi-scales was introduced, and the efficiency was also proved in full. In this paper, fault section discrimination and fault location algorithm using noise cancellation technique were tested by ATP simulation on real power cable systems. From these results, the fault can be located even in very difficult and complicated situations such as different inception angle and fault resistance.