说明：  由于离散傅里叶变换在高频部分会出现混频，使得傅里叶变换存在两个像，使用非均匀傅里叶变换可解决此问题
(Because of the mixing of discrete Fourier transform in high frequency, there are two images in the Fourier transform, which can be solved by using non-uniform Fourier transform.)