clear
clc
close all
a=imread('d:\于秀明1031001755\Miss.bmp');
subplot(231);
imshow(a);
title('灰度級256');
%灰度級64
a=double(a);
 for i=1:256;
   for j=1:256;
        b(i,j)=round(a(i,j)/4-0.5);
    end
end
subplot(232);
imshow(b,[]);
title('灰度級64');
%灰度級16
for i=1:256;
    for j=1:256;
        c(i,j)=round(a(i,j)/16-0.5);
    end
end
subplot(233);
imshow(c,[]);
title('灰度級16');
%灰度級8
for i=1:256;
    for j=1:256;
        d(i,j)=round(a(i,j)/32-0.5);
    end
end
subplot(234);
imshow(d,[]);
title('灰度級8');
%灰度級4
for i=1:256;
    for j=1:256;
        e(i,j)=round(a(i,j)/64-0.5);
    end
end
subplot(235);
imshow(e,[]);
title('灰度級4');
%灰度級2
for i=1:256;
    for j=1:256;
        f(i,j)=round(a(i,j)/128-0.5);
    end
end
subplot(236);
imshow(f,[]);
title('灰度級2');