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How to use FFT2

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05 Jul 2006 (Updated )

How to apply the 2D FFT functions in Matlab

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Description

The note explains in detail how to apply the Matlab 2-dimensional FFT for filtering of two-dimensional signals, e.g. images.
It is shown how to connect the output from fft2 to the actual Fourier transform of the signal, and in particular how transfer functions of simple filters may be coded.

MATLAB release MATLAB 7.1.0 (R14SP3)
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Comments and Ratings (12)
02 Jun 2015 Katarzyna Wieciorek

Can you tell me more about symbols that you used?

What is K0, cut-off frequency? What are other K and why like this?

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02 Jun 2015 Katarzyna Wieciorek  
23 Apr 2008 emine doganay  
28 Jan 2008 Vitaly Minchenya

I applied it as follows:

%****FFT Low Pass Filter****%
%Array dimensions
M = 1024;
N = 1024;
%Sampling intervals
dx = 1;
dy = 1;
%Characteristic wavelengths
KX0 = (mod(1/2 + (0:(M-1))/M , 1) - 1/2);
KX1 = KX0 * (2*pi/dx);
KY0 = (mod(1/2 + (0:(N-1))/N , 1) - 1/2);
KY1 = KY0 * (2*pi/dx);
[KX,KY] = meshgrid(KX1,KY1);
%Filter formulation
K0 = 0.16;
T = (KX.*KX + KY.*KY < K0^2);
%Filter Application
bwmofilt = ifft2(T.*fft2(bwmo));
imwrite(bwmofilt,'4.filtered.jpg');
%******END of FFT Low Pass Filter******%

28 Jan 2008 Vitaly Minchenya

Very helpful.

18 Jan 2008 asafd asdfasdf  
29 Mar 2007 HYOJOON CHOI

good

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28 Jan 2007 ARJUN KUMAR

helping material

03 Jan 2007 Vishnuvenkatesh Dhage  
18 Jul 2006 George Caminha

A good material...

06 Jul 2006 S Mai  
05 Jul 2006 urs (us) schwarz

since this PDF submission does not provide any usable code it should be tagged as a WHITE PAPER
us

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