03_smoothx

03_smoothx - Other Arrangements center pixel: 1 vs 5...

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Smoothing Spatial Filters COMP344 COMP344 Smoothing Spatial Filters
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Spatial Filter Spatial filtering (as opposed to frequency domain filter) Types linear nonlinear COMP344 Smoothing Spatial Filters
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Spatial Filtering using a Mask COMP344 Smoothing Spatial Filters
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Spatial Filtering using a Mask. .. Mask ( convolution mask) f ( x , y ) is centered around z 5 w i : mask coefficient Response of a linear mask, R g ( x , y ) = R = 9 i =1 w i z i ( convolution ) note that the result can be larger than the valid output range ( L - 1) can pre-scale the filter scale factor = ( w i ) - 1 COMP344 Smoothing Spatial Filters
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Motivating Example COMP344 Smoothing Spatial Filters
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Smoothing Filters blurring: removal of small details noise reduction: item removal of noise in an image COMP344 Smoothing Spatial Filters
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Smoothing Filters. .. Often called lowpass filters filter lets low frequencies pass stops high frequencies Spatial domain Frequency domain COMP344 Smoothing Spatial Filters
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Smoothing (Averaging) Filter Extends to larger filters COMP344 Smoothing Spatial Filters
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Window Size COMP344 Smoothing Spatial Filters
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Examples COMP344 Smoothing Spatial Filters
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Unformatted text preview: Other Arrangements center pixel: 1 vs 5 COMP344 Smoothing Spatial Filters Linear vs. Non-linear g ( x , y ) = 9 X i =1 w i z i Linear filters linear operation Nonlinear filters examine neighbors using various orderings often use Rank or Order statistics COMP344 Smoothing Spatial Filters Median Filter Very popular non-linear filter Find the median of the window Preserves edges Removes impulse noise, avoids excessive smoothing COMP344 Smoothing Spatial Filters Example Original;Noisy;Low-pass;Median Often referred to as de-speckle operation COMP344 Smoothing Spatial Filters Window Size 3x3;5x5;9x9;15x15 COMP344 Smoothing Spatial Filters Iterative Smoothing Local averaging if you perform it over and over, eventually converges to an image with constant intensity Median filter if you perform it over and over, eventually the image will not change converges to an image invariant to the filter COMP344 Smoothing Spatial Filters...
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This note was uploaded on 09/24/2010 for the course COMP 344 taught by Professor Albertk.wong during the Fall '09 term at HKUST.

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03_smoothx - Other Arrangements center pixel: 1 vs 5...

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