`fft2`

Two-dimensional discrete Fourier transform.

Category: Mathematics > Fourier Analysis and Filtering

Syntax

Y = fft2(X)

Transforms along the first two dimensions.

Y = fft2(X, m, n)

Zero-pads or truncates X to m rows and n columns first.

Description

fft2(X) is the same as fft(fft(X).').': a one-dimensional transform down every column followed by one along every row. It is the basis for frequency-domain image filtering and for fast 2-D convolution.

For N-D input, each page (the slices over dimensions 3 and up) is transformed independently. Use fftshift to move the zero-frequency term to the center for display.

Input arguments

X: Numeric matrix or N-D array.
m, n: Number of rows and columns of the transform.

Output arguments

Y: Two-dimensional spectrum. Y(1,1) is the sum of all elements.

Example

Small matrix and padding

fft2([1 2; 3 4])
size(fft2([1 2; 3 4], 3, 3))

Output

fft2