说明：  matlab下对图像进行fft变换，平滑，锐化，中心化傅立叶正变换得到大正方形，小正方形，斜正方形。对其频谱进行中心化处理。图像的平滑和锐化，利用拉普拉斯算子。
(Matlab right image fft transform, smoothing, sharpening, is the center of the Fourier transform large square, small square, ramp square. Its spectrum treatment center. Image sharpening and smoothing, using Laplace operator.)