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Re: Fast local contrast calculations? [message #86300 is a reply to message #86294]

Wed, 23 October 2013 22:33

Moritz Fischer
Messages: 32
Registered: June 2013

Member

Hi Ken,
my suggestion is to 'align' the tile elements with reform:

IDL> t = randomn(1, 6,6)
IDL> print, t
IDL> print, max(max( reform( t, 2, 6/2, 2, 6/2 ), D=1),D=2)

You could even remove the second max, by using transpose and another
reform, but I think transpose will cost you...

Let me know what you end up with!

mo

Am 23.10.2013 20:28, schrieb kagoldberg@lbl.gov:
> I'm looking for a quick way to calculate local contrast across a
> (2048,2048) image. The end result could be a 64x64 element array, for
> example, and that would be fine.
>
> Speed-wise, calculating local averages with rebin() are lightning
> fast. Even median(image,N) is pretty fast. But is there a similar
> high-speed way to get minimum and maximum values within each 'tile'
> without having to write a loop? It's as though I need a rebin_min()
> and rebin_max() where the min and max values are preserved within the
> sampled output array.
>
> I'd love to hear any suggestions. Thanks, Ken
>

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[Message index]

		Fast local contrast calculations? By: kagoldberg on Wed, 23 October 2013 11:28
		Re: Fast local contrast calculations? By: Moritz Fischer on Wed, 23 October 2013 22:33
		Re: Fast local contrast calculations? By: kagoldberg on Thu, 24 October 2013 20:35

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