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. I