Why are the results produced by fft2 and those produced by fft different?

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William
William 2017-7-29
编辑： William 2022-9-13
I conducted Fourier transform on an imag through two operations:
Firstly:
pic='pic.jpg';
pic_read=rgb2gray(double(imread(pic)));
results1= fft2(pic_read);
Secondly:
for c=1:size(pic_read,2)
fft_column(:,c)=fft(pic_read(:,c));
end
for r=1:size(pic_read,1)
results2(r,:)= fft(fft_column(r,:));
end
isequal(results1,results2)
ans =
0
I want to know why the results of the two above operations are different ?
Thanks

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回答（1 个）

Ahmed raafat
Ahmed raafat 2017-7-30
use tic toc commands
tic
... your code...
t=toc; % time in second
freq=your images/t

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