| Re: "Max()" filter? [message #29707 is a reply to message #29581] |
Fri, 08 March 2002 10:30  |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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"Dick Jackson" <dick@d-jackson.com> writes:
> "trouble" <the_cacc@hotmail.com> wrote in message
> news:5f9f0a23.0203070323.4c32551b@posting.google.com...
>> You could code this up quicker than it took to write the message...
>
> trouble,
>
> Certainly a brute-force method with loops that go over every array element
> and do a Max operator over the appropriate nxn (or less) kernel is easy, but
> I think that it is somewhat inefficient for the 1024x1024 datasets I have in
> mind where the kernel might be around 30x30. In trying it, it runs in about
> 14 seconds.
>
> Perhaps I should have added the word "efficient" somewhere, where I would
> like performance on the same order as the Smooth function, which takes 0.151
> seconds. I believe Smooth saves huge amounts of time by overlapping
> calculations. I don't see how an efficient local max filter like this would
> be trivial to write in IDL, that's why I was asking.
Hi Dick--
These are the kinds of things that JD Smith, Wayne Landsman (?) and I
have wished for before. I believe it's nontrivial to do in IDL as it
exists today.
Craig
--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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