Howtosignalprocessing
Why is Fftshift necessary?
It is useful for visualizing a Fourier transform with the zero-frequency component in the middle of the spectrum. 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.
What does fft shift do?
Y = fftshift( X ) rearranges a Fourier transform X by shifting the zero-frequency component to the center of the array. If X is a vector, then fftshift swaps the left and right halves of X . If X is a matrix, then fftshift swaps the first quadrant of X with the third, and the second quadrant with the fourth.
