当前信号处理中，对频谱的研究不断深入，本书中讲述如何使用快速傅里叶变化进行频谱变换，和图像相关性分析，信号处理- How to use FFT2 The note explains in detail how to apply the Matlab 2-dimensional FFT for filtering of two-dimensional signals, e.g. images. It is shown how to connect the output from fft2 to the actual Fourier transform of the signal, and in particular how transfer functions of simple filters may be coded.