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Min/Max filter

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4.0 | 8 ratings Rate this file 78 Downloads (last 30 days) File Size: 28.7 KB File ID: #24705 Version: 1.7

Min/Max filter

by

Bruno Luong (view profile)

 

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 (10)
15 Dec 2014 Christopher Volpe

Stupid question: How is this different from simply doing an erosion (min) or dilation (max)? Or is this just for people who don't have the image processing toolbox?

Comment only
08 Dec 2014 ali

ali (view profile)

 
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

shi (view profile)

 
03 Oct 2010 Michael Teo

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

03 Oct 2010 Bruno Luong

Bruno Luong (view profile)

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')

Comment only
24 Mar 2010 Tobias

Tobias (view profile)

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

Updates
13 Jul 2009 1.1

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 1.2

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

21 Sep 2009 1.3

Correct BUG of cropping the index array when shape is SAME

21 Sep 2009 1.4

Acknowledgment

22 Sep 2009 1.5

Cleaner algorithm for same shape filtering

26 Sep 2009 1.6

description

01 Dec 2009 1.7

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

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