figure;imshow(i);
G=fft2(double(i));
FG=abs(fftshift(G));
PG=angle(G);
IFG=ifft2(FG);
IPG=ifft2(exp(j*PG));
figure;
subplot(2,2,1);
imshow(log(FG+1),[])%顯示頻譜幅度
title('圖像頻譜幅度');
subplot(2,2,2);
imshow(angle(fftshift(G)),[])
title('圖像相位');
%---------------------------
subplot(2,2,3);
imshow(log(1+abs(IFG)),[]);
title('圖像頻譜幅度的逆變換');
subplot(2,2,4);
imshow(IPG,[]);
title('圖像相位的逆變換');
%---------------------------
M=ifft2(abs(G).*exp(j*PG));
figure;imshow(M,[]);