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Currently, I working on a assignment to obtain few frames from a movie file played in Matlab. A 3D Matrix was created in parameter X,Y and time. But I been asked to determine the frequency in time by using FFT and IFFT.

My problem is how to plot the graph by using FFT and IFFT on 3D matrix to determine the frequency in time dimension? If someone can provide part of the matlab code will very appreciate.

E.Lee
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1 Answers1

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Suppose your matrix is A(x,y,t), call

A = ifft(fft(A, NFFT, 3), size(A,3), 3);

to do the transform on time domain. NFFT is the total points needed, usually padding with the size of 2^n.

In fft(A, NFFT, 3), your frequency axis will be (0:NFFT)/NFFT*Fs, where Fs = 1/T, T is the time interval of your frames.

lennon310
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