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fftshift | Examples See Also |
Shift DC component of fast Fourier transform to center of spectrum
Y = fftshift(X)
Y = fftshift(X)
rearranges the outputs of fft
, fft2
, and fftn
by moving the zero frequency component to the center of the array.
For vectors, fftshift(X)
swaps the left and right halves of X
. For matrices, fftshift(X)
swaps quadrants one and three of X
with quadrants two and four. For higher-dimensional arrays, fftshift(X)
swaps "half-spaces" of X
along each dimension.
For any matrix X
Y = fft2(X)has
Y(1,1)
=
sum(sum(X))
; the DC component of the signal is in the upper-left corner of the two-dimensional FFT. For
Z = fftshift(Y)this DC component is near the center of the matrix.
fft
One-dimensional fast Fourier transform
fft2
Two-dimensional fast Fourier transform
fftn
Multidimensional fast Fourier transform