说明：  本实验要求开发一个2-D FFT程序包，使其可以应用于后续的几个实验。这个程序需要完成的功能是用因子（-1）^(x+y)乘以输入图像以实现滤波的中心变换，并还要求用一个实矩阵乘以一个复数矩阵通过调用两个图像的乘法程序来实现对应元素的相乘，同时计算反傅立叶变换，得到的结果乘以（-1）^(x+y)并取其实部最后计算频谱。实验中用到傅立叶变换的基本公式，通过实验我们可以更加深刻的理解频域滤波的基础。
(The experiment calls for the development of a 2-D FFT package so that it can be applied to a number of follow-up experiment. This process needs to be done is to factor the function (-1) ^ (x+ y) multiplied by the input image to achieve the center of filter change, and also requires a real matrix multiplied by a complex matrix by calling the two images of the multiplication process to achieve multiplication of the corresponding elements, calculating the anti-Fourier transform at the same time, the result multiplied by (-1) ^ (x+ y) and check the final calculation of the Department of the spectrum in fact. Fourier transform experiment used the basic formula, we can experiment more profound understanding of the basis of frequency domain filtering.)