有个问题请问一下

clear,clc
a=imread('E:\1.bmp');
grid on
figure(1)
imshow(a,[])
afft=fft2(double(a));
aabs=abs(afft);
aabss=fftshift(aabs);
figure(2)
imshow(aabss,[])
colormap(gray);
colorbar
figure(3)
plot(aabss)
colormap(gray);
figure(4)
meshc(aabss)
maxx1=max(max(aabss));
这个程序有个问题请帮忙解决一下