离散傅立叶变换 DFT

%离散傅立叶变换 DFT

x=ones(100,100);
x(30:70,48:52)=0;
f=fft2(x);
%直接FFT
f1=abs(f);
%阵元平移后FFT
i1=[1,-1;-1,1];
i2=repmat(i1,50,50);
y=x.*i2;
f2=abs(fft2(y));
subplot(3,1,1),imshow(x,'notruesize')
subplot(3,1,2),imshow(f1);colormap(jet);colorbar;
subplot(3,1,3),imshow(f2);colormap(jet);colorbar;