Signal Processing Toolbox

fftshift

Rearrange the outputs of the FFT functions.

Syntax

y = fftshift(x)

Description

y = fftshift(x) rearranges the outputs of fft and fft2 by moving the zero frequency component to the center of the spectral density, which is sometimes a more convenient form.

For vectors, fftshift(x) returns a vector with the left and right halves swapped.

For arrays, fftshift(x) swaps quadrants one and three with quadrants two and four.

The fftshift function is part of the standard MATLAB language.

Examples

For any array 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)

the DC component is near the center of the matrix.

See Also

fft	One-dimensional fast Fourier transform.
fft2	Two-dimensional fast Fourier transform.

fftfilt

filter