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"Max()" filter? [message #29581]

Wed, 06 March 2002 10:30

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

Hi all,

Given these well-known filters for 2D array 'x':

Smooth(x, n)
Median(x, n)
Convol(x, [nxn kernel])

All of them calculate for each element in x (in general) some function of an
nxn set of elements around that element. For the three, the function is

Mean()
Median()
WeightedSum()

I'd like a filter that uses the Max() function, so that this array:

1 4 2 4 3
3 5 2 1 4
5 7 4 3 1
3 5 1 1 2
3 1 2 3 1

filtered with width 3 gives:

5 5 5 4 4
7 7 7 4 4
7 7 7 4 4
7 7 7 4 3
5 5 5 3 3

(I think! :-)

Even better would be to supply any function in general. Is there a name for
this? Is there any free IDL code for this out there? :-) Google tells me
that something called "local max filter" was discussed here once, but that's
not really what I want.

Many thanks for any leads.

Cheers,
--
-Dick

Dick Jackson / dick@d-jackson.com
D-Jackson Software Consulting / http://www.d-jackson.com
Calgary, Alberta, Canada / +1-403-242-7398 / Fax: 241-7392

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[Message index]

		"Max()" filter? By: Dick Jackson on Wed, 06 March 2002 10:30
		Re: "Max()" filter? By: JD Smith on Fri, 08 March 2002 18:36
		Re: "Max()" filter? By: Craig Markwardt on Fri, 08 March 2002 10:30

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