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Blurring and Local Blurring. 姓名 : 張珮毓 授課教師:張顧耀 教授 報告日期: 2007/06/12. Outline. Introduction Blurring Discrete Gaussian Binomial Blurring Recursive Gaussian IIR Local Blurring. Introduction. This section describes several methods that can be applied to reduce noise on images. Blurring - PowerPoint PPT Presentation
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Blurring and Local Blurring
姓名 : 張珮毓授課教師:張顧耀 教授報告日期: 2007/06/12
Outline Introduction Blurring
Discrete GaussianBinomial BlurringRecursive Gaussian IIR
Local Blurring
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Introduction This section describes several methods that
can be applied to reduce noise on images. Blurring
Blurring is the traditional approach for removing noise from images.
The effect of blurring on the image spectrum is to attenuate high spatial frequencies.
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Outline Introduction Blurring
Discrete GaussianBinomial BlurringRecursive Gaussian IIR
Local Blurring
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Header: #include "itkDiscreteGaussianImageFilter.h"
filter->SetVariance( gaussianVariance ); filter-
>SetMaximumKernelWidth( maxKernelWidth );
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Discrete Gaussian
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2
2
2
1
x
exG
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Discrete Gaussian
Effect of the DiscreteGaussianImageFilter on a slice from a MRI proton density image of the brain.
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7Variance=3 maxKernelWidth=3*3
Discrete Gaussian
Variance=7maxKernelWidth=3*3
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Discrete Gaussian
Variance=3 maxKernelWidth=5*5
Variance=3 maxKernelWidth=7*7
Binomial Blurring Binomial Blurring computes a nearest
neighbor average along each dimension The process is repeated a number of times, as
specified by the user.
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Binomial filters. 1D versions
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Binomial Blurring
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11b
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In principle, after a large number of iterations the result will approach the convolution with a Gaussian.
Header: #include "itkBinomialBlurImageFilter.h"
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Binomial Blurring
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Binomial Blurring
Repetitions=2 Repetitions=8
Finite Impulse Response (FIR) Infinite Impulse Response (IIR)
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Recursive Gaussian IIR
只延伸到有限距離 (FIR) 延伸到影像邊界 (IIR)
Recursive Gaussian IIR Header:
#include "itkRecursiveGaussianImageFilter.h”
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Recursive Gaussian IIR
Sigma=3 Sigma=5 Sigma=7
Outline Introduction Blurring
Discrete GaussianBinomial BlurringRecursive Gaussian IIR
Local Blurring
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Local Blurring In some cases it is desirable to compute
smoothing in restricted regions of the image, or to do it using different parameters that are computed locally.
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ItkSoftwareGuide http://www.engr.udayton.edu/faculty/jloomis/
ece563/notes/filter/smooth/smooth.html http://ssip2003.info.uvt.ro/lectures/gui/
smoothing_techniques_in_image_processing.ppt
http://www.cee.hw.ac.uk/hipr/html/gsmooth.html
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參考資料