| FFT transforms for images [message #11509] |
Wed, 01 April 1998 00:00 |
Michael A. Wirth
Messages: 5
Registered: April 1997
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Junior Member |
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Hi,
I'd like to do some processing using a FFT transform. Basically all I
want to do is calculate the FFT
of an image, histogram equalize the power spectrum and then inverse the
FFT, producing what is in
effect an attentuated version of my image. I assume the built-in FFT
routine in 1D... does anybody have
any suggestions short of writing a 2D FFT.
thanks,
Michael
------------------------------------------------------------ ---------------
Michael A. Wirth, M.Sc.(CompSci) B.Sc.(Hons)
Biomedical Engineering Group
Centre for High Performance Computer Systems
Dept. of Computer Systems Engineering
RMIT University
Melbourne 3001, Victoria, Australia +61-3-9660-5340 [fax]
s9601460@minyos.its.rmit.edu.au +61-3-9660-5361 [ph]
------------------------------------------------------------ ---------------
The difference between participation and commitment
is illustrated at breakfast. The chicken participates.
The pig is committed.
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| Re: FFT transforms for images [message #11517 is a reply to message #11509] |
Tue, 31 March 1998 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Michael A. Wirth (Michael.Wirth@cse.rmit.edu.au) writes:
> I'd like to do some processing using a FFT transform. Basically all I
> want to do is calculate the FFT
> of an image, histogram equalize the power spectrum and then inverse the
> FFT, producing what is in
> effect an attentuated version of my image. I assume the built-in FFT
> routine in 1D... does anybody have
> any suggestions short of writing a 2D FFT.
I've found from painful personal experience that it is
usually safer to read the documentation than to make
an assumption about how IDL does or does not work. :-)
In this case, although the FFT documentation inexplicably
does not say *specifically* that it works with 2D arrays,
it does say that the output array "has the same dimensions
as the input array." I take this to mean that it is safe
to process images with the FFT function. In fact, you can
find information on my web page about how to create
frequency filters and image power spectrums using the
FFT function.
Cheers,
David
-----------------------------------------------------------
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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