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Min/Max filter

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Min/Max filter

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12 Jul 2009 (Updated )

Multidimensional non-linear min/max filtering

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Description

The filter computes the minima and/or maxima of an array over sliding window with a given size.

Multidimensional array is fully supported: running filter in 1D, 2D filter for image processing applications (erosion/dilatation), 3D and more.

This package has been implemented with a special care on the running speed: the MEX engine uses an algorithms that requires no more than three (3) comparisons per element and per dimension in all configurations.

All numerical and logical class arrays are supported.

Contributor (beside author) is Vaclav Potesil

Acknowledgements

This file inspired Free Knot Spline Approximation.

MATLAB release MATLAB 7.8 (R2009a)
Other requirements MEX correctly setup NO image processing is required Download a tiff file for Lena's demo
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Comments and Ratings (8)
02 Nov 2014 seongjin

So far, this is the fastest that I know. Thank you.

24 May 2014 Wathsala Ranasinghe  
02 Sep 2013 Gerald Grabner

Fast!

20 Oct 2011 Qiao Liyong  
06 Oct 2011 shi  
03 Oct 2010 Michael Teo

Thanks for sharing, its make sense and it solved my problem. :)

03 Oct 2010 Bruno Luong

I copy the question from Michael Teo: Does it handle NaN data?

<QUOTE>
ePeriod = 3;
eData = [ 5;1;3;NaN;8;2;3;NaN;1;9 ];
minmaxfilt(eData, ePeriod, 'max', 'valid');

Actual output:
[5;3;3;NaN;8;3;3]

If we take NaN as a empty data, the expected output is:
[5;3;8;8;8;3;3]
</ENDQUOTE>

The answer is "no". The work around id to replace NaN by -Inf for running max and +Inf for running min.

eData(isnan(eData))=-inf
minmaxfilt(eData, ePeriod, 'max', 'valid')

24 Mar 2010 Tobias

Nice Max-Filter. Works faster than implementation of Frederico D'Almeida and seems to be correct.

Updates
13 Jul 2009

Correct a bug that causes crash on 64-bit plateform
Additional memory check in one MEX function
Friendly matlab gateway for 1D min/max filtering

20 Sep 2009

New feature: Possibly to output corresponding indexes arrays (suggested by a user) + slight improvement of the Lemire's engine.

21 Sep 2009

Correct BUG of cropping the index array when shape is SAME

21 Sep 2009

Acknowledgment

22 Sep 2009

Cleaner algorithm for same shape filtering

26 Sep 2009

description

01 Dec 2009

Correct a small bug when "WIN" is a scalar and input array is vector (error wrongly issued)

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