图象变换　从傅立叶变换的频谱图中可以看出，提高分辨率以后，其边缘更加平滑，锯齿状明显减弱。但其傅立叶变换后的图像没有明显改变。 3》DC系数移动 其系数移动以后，频谱分量都集中到了频谱的中间。 4》滤波器频率响应(Image transform,As can be seen from the spectrum diagram of Fourier transform, the edge is smoother and the serrated is significantly reduc