Global Filter Networks for Image Classification Supplementary Material A Discrete Fourier transform

In this section, we will elaborate on the derivation and the properties of the discrete Fourier transform. A.1 From Fourier transform to discrete Fourier transform Discrete Fourier transform (DFT) can be derived in many ways. To name a few basic ones, the FT of a unit impulse function (a.k.a. However, we rarely deal with continuous signal in the real application. The extension from 1D DFT to 2D DFT is straightforward.