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## How to use FFT2

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How to apply the 2D FFT functions in Matlab

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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.

Katarzyna Wieciorek

### Katarzyna Wieciorek (view profile)

Can you tell me more about symbols that you used?

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

Katarzyna Wieciorek

### Katarzyna Wieciorek (view profile)

emine doganay

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******%

Vitaly Minchenya

asafd asdfasdf

HYOJOON CHOI

good

ARJUN KUMAR

helping material

Vishnuvenkatesh Dhage

George Caminha

A good material...

S Mai

urs (us) schwarz

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

##### MATLAB Release
MATLAB 7.1.0 (R14SP3)