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Re: fft application? [message #31571]

Fri, 02 August 2002 10:18

Don J Lindler
Messages: 19
Registered: April 2001

Junior Member

"helen" <bin_zheng_99@yahoo.com> wrote in message
news:958f2cda.0208020646.3112c408@posting.google.com...
> Hi, All,
>
> I try to do template matching using IDL and I run the IDL code:
> ...
> img4 = rotate (img3, 2)
> Result = float (fft(fft(img) * fft(img4),/inverse))
> ...
>
> based on the code used in Matlab image processing toolbox:
> C = real(ifft2(fft2(bw) .* fft2(rot90(a,2),256,256))); (bw, a are
> two images)
> the max(C) is 51.
>
> But on IDL55 the Max value is 0.00013. I use the same images as in
> the Mablab.
>
> So, I wonder are there some serious differences between the fft in
> IDL and in Matlab? How can I improve my program to get good result?
>
> Thanks very much for any suggestions, ideas, or help,
>
> Helen

Try

Result = float (fft(fft(img) * fft(img4),/inverse))*n_elements(img)

Don

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Re: fft application?

By: Don J Lindler on Fri, 02 August 2002 10:18

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