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Topic: Fourier shift theorem
Replies: 1   Last Post: Dec 13, 2012 2:58 PM

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Posts: 22
Registered: 9/18/08
Fourier shift theorem
Posted: Dec 10, 2012 6:24 PM
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Dear all,

I'm currently trying to understand the 2d fourier shift theorem.

According to what I've learnd so far a translation in the image space leads to differences in phase but not the magnitude in frequency space.

I tried to demonstrate this with a little example but it only worked for shifts in rows but not in columns. Here's the little demo (I'm only showing the magnitude plots here)

clear all
close all
Iin = zeros(128);
Y = fft(Iin);
figure, imagesc(fftshift(log10(abs(Y))));

Iin = zeros(128);
Y = fft(Iin);
figure, imagesc(fftshift(log10(abs(Y))));

Iin = zeros(128);
Y = fft(Iin);
figure, imagesc(fftshift(log10(abs(Y))));

In my opinion all 3 magnitude plots should yield the same result.
Can anyone explain me what I'm doing wrong here?

thank you very much for your help,
best regards,

Date Subject Author
Read Fourier shift theorem
Read Re: Fourier shift theorem
Jeff Orchard

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