应用傅立叶变换对图像处理，实现查看图像的功率谱，以及功率谱经过巴特沃斯高通、低通和高斯高通、低通滤波器后图像的功率谱，再把功率谱还原为图像的功能。-Fourier transform for image processing, see the image of the power spectrum, and the power spectrum after Butterworth high-pass, low-pass and high-pass Gaussian low-pass filter of the image after power spectrum, and then restore the power spectrum of the image.