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Topic: 2D fourier transform filter
Replies: 1   Last Post: Dec 10, 2012 4:47 PM

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 JK Posts: 6 Registered: 12/9/12
Re: 2D fourier transform filter
Posted: Dec 10, 2012 4:47 PM

"JK" wrote in message <ka3e6u\$gi4\$1@newscl01ah.mathworks.com>...
> I am trying to remove low frequency bands from an image after transforming it using 2D fast fourier. I can identify individual components of the transformed image, but cannot yet work out how to filter only components higher than a certain frequency threshold and then reconstruct the original image using only those frequencies.
>
> Say, for example, I have the following 5 x 5 image matrix, x:
>
> 1 2 3 4 5
> 1 2 3 4 5
> 1 2 3 4 5
> 1 2 3 4 5
> 1 2 3 4 5
>
> I subtract out the mean and compute the FFT:
> x = x - mean(mean(x)); X = fft(x);
>
> But then how would I filter only frequencies of X above a a threshold, t, and reconstruct the image using only those frequencies to give Y?
>

Sorry I meant X = fft2(x);

Date Subject Author
12/9/12 JK
12/10/12 JK