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Two-dimensional fast Fourier transform
Y = fft2(X) Y = fft2(X,m,n)
Y = fft2(X)
performs the two-dimensional FFT. The result Y is the same size as X.
Y = fft2(X,m,n)
truncates X, or pads X with zeros to create an m-by-n array before doing the transform. The result is m-by-n.
fft2(X) can be simply computed as
fft(fft(X).').'This computes the one-dimensional FFT of each column
X, then of each row of the result. The time required to compute fft2(X) depends strongly on the number of prime factors in [m,n] = size(X). It is fastest when m and n are powers of 2.
fft One-dimensional fast Fourier transform
fftshift Rearrange the outputs of fft and fft2
ifft2 Inverse two-dimensional fast Fourier transform