%利用radon函數(shù)和iradon函數(shù)構(gòu)造一個(gè)簡單圖像的投影并重建圖像
%產(chǎn)生256個(gè)灰度等級(jí)的大腦圖
P = phantom(256);
imshow(P)

%計(jì)算3個(gè)不同部分的大腦圖的Radon變換
theta1 = 0:10:170;
[R1,xp] = radon(P,theta1);
theta2 = 0:5:175; 
[R2,xp] = radon(P,theta2);
theta3 = 0:2:178; 
[R3,xp] = radon(P,theta3);

%顯示Shepp-Logan大腦幻影圖的有90條投影光束的Radon變換圖形
figure, imagesc(theta3,xp,R3); colormap(hot); colorbar
xlabel('\theta'); ylabel('x\prime');

%利用R1、R2和R3分別進(jìn)行Shepp-Logan大腦幻影圖的重構(gòu)
I1 = iradon(R1,10);
I2 = iradon(R2,5);
I3 = iradon(R3,2);
imshow(I1)
figure, imshow(I2)
figure, imshow(I3)