comp.lang.idl-pvwave archive: archive » FFT OF A NON RECTANGULAR IMAGE

Home » Public Forums » archive » FFT OF A NON RECTANGULAR IMAGE

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: FFT OF A NON RECTANGULAR IMAGE [message #63164 is a reply to message #63086]

Tue, 28 October 2008 11:12

Kenneth P. Bowman
Messages: 585
Registered: May 2000

Senior Member

In article
<4a2c3474-def0-48fc-8611-05635d75f05d@v39g2000pro.googlegroups.com>,
legall_alice@yahoo.fr wrote:

> Hi all:
>
> How can we do a FFT on a 2D-function that defines a non-rectangular
> image?
>
> Here is an example: the region of interest is an inclined ellipse. To
> be able to apply FFT(array,1), I created an array where all the pixels
> around the ellipse are set to the value zero. I would like to exclude
> from the FFT process the black area (zero value pixels) surrounding
> the ellipse.
>
>
> Thank you a lot in advance for your help,
>
> Alice Le Gall

By their nature, Fourier transforms are global.

Can you map the ellipse to a rectangle? (http://en.wikipedia.org/wiki/Conformal_map)

Ken Bowman

Report message to a moderator

[Message index]

		FFT OF A NON RECTANGULAR IMAGE By: legall_alice on Tue, 28 October 2008 09:23
		Re: FFT OF A NON RECTANGULAR IMAGE By: legall_alice on Tue, 28 October 2008 20:56
		Re: FFT OF A NON RECTANGULAR IMAGE By: R.G. Stockwell on Tue, 28 October 2008 18:35
		Re: FFT OF A NON RECTANGULAR IMAGE By: pgrigis on Thu, 30 October 2008 08:10
		Re: FFT OF A NON RECTANGULAR IMAGE By: Kenneth P. Bowman on Tue, 28 October 2008 11:12

Previous Topic:	New Widgets Needed
Next Topic:	Re: position plot in iplot

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sun Oct 12 10:04:45 PDT 2025

Total time taken to generate the page: 1.05989 seconds