Difference between a Linear and nonlinear Filter in Image processing?
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What is the main difference between the linear an nonlinear filters that is being used in Image processing for the reduction of noise.How can i realize a filter is linear or not?
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Answers (4)
Image Analyst
on 22 Dec 2018
A linear filter is one that can be done with a convolution, which is just the linear sum of values in a sliding window. It can be done equivalently in the Fourier domain by multiplying the spectrum by an image. A blurring filter where you move over the image with a box filter (all the same values in the window) is an example of a linear filter.
A non-linear filter is one that cannot be done with convolution or Fourier multiplication. A sliding median filter is a simple example of a non-linear filter.
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Ramzan Shahid khan
on 11 Feb 2020
Linear filtering is the filtering method in which the value of output pixel is linear combinations of the neighbouring input pixels. it can be done with convolution.For examples, mean/average filters or Gaussian filtering.
A non-linear filtering is one that cannot be done with convolution or Fourier multiplication. A sliding median filter is a simple example of a non-linear filter.
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Soe Lei Hnin
on 8 Aug 2019
Let me ask a question.I'm a little bit confusing about gaussian kernel.I found a size of [1×11] gaussian kernel.I have no idea how it got.
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Soe Lei Hnin
on 9 Aug 2019
Edited: Image Analyst
on 9 Aug 2019
From Barcode recognition code from matlab example.Here it is.
h=single([0.022191,0.045589,0.079811,0.119065,0.151361,0.163967,0.151361,0.119065,0.079811,0.045589,0.022191])
That's used as gaussian filter in that algorithm. Is there any equation to generate those values? I tried with fspecial. I failed.Thanks for your answer.
Image Analyst
on 9 Aug 2019
If fspecial doesn't make it, then you can try to fit a Gaussian with fitnlm. See attached example.
Sudaroli Sandana
on 20 Aug 2020
In Linear Spatial filtering the spatial mask in convoltion process is used.In Non Linear , the ordering mechanism is used to produce output pixel ie to replace the centre pixel
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