Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: anybody got a complex 2-D median filter script they can share?
Replies: 7   Last Post: Nov 13, 2012 5:55 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Cameron

Posts: 4
Registered: 3/4/11
Re: anybody got a complex 2-D median filter script they can share?
Posted: Mar 4, 2011 11:42 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

"Matt J" wrote in message <ikr2rg$345$1@fred.mathworks.com>...
> "Cameron " <cameron.matthews@yahoo.com> wrote in message <ikr234$d89$1@fred.mathworks.com>...
> >
> >
> > Thats essentially what I was doing before. I think it violates some part of signal processing to do it that way though and is just filtering out a bunch of stuff I don't want serendipitously. I am trying to preserve a phase characteristic of the complex imaginary data. there are a few papers on IEEE about the application for complex weighted median filters, but frankly I don't think I have time to digest the math and get a script written.

> =============
>
> So your 2D image is frequency domain data? Maybe you just want to filter the amplitude response and keep the phase, e.g.,
>
> X=medfilt2(abs(X)).*angle(X)
>
> In any case, I doubt you're going to find anyone on here (quickly) who is familiar with the few obscure IEEE papers that you've alluded to. You'd best start describing your problem in enough detail for people to make suggestions.

=================================
Fair enough... I am looking at two views of the same area. my data is coherently sampled so I have phase data. because I am looking at the area from different vantage points I have a different grazing angle and there is speckle associated with the phase offset.

I don't want to discard the phase information entirely so I don't want to look at the magnitude. I found for the application a median filter works very well, but I want analyze the phase data with it and the standard medfilt2 algorithm only works on real numbers.

since phase wraps around, I don't think a conventional median filter will necessarily provide any meaningful data.

SO - I guess an addendum to this request for help would be:

if I median filter the amplitude,then separately median filter the phase or angle and then resolve the two datasets to a complex number, is the math in fact non-valid?



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.