clear all;
close all;
I=imread('Lena.bmp');
rect=[210,40,15,15];
I2=imcrop(I,rect);
h=fspecial('gaussian',16,4);
r=h.*double(I2);
w=fftshift(fft2(double(r),256,256));
am=abs(w);
subplot(2,2,1);imshow(I);title('Lena原圖');
subplot(2,2,2);imshow(I2);title('截取局部圖形');
subplot(2,2,3);imshow(uint8(log(am)),[]);title('Fourier變換后');