clear
clc
close all
a=imread('d:\于秀明1031001755\Miss.bmp');
a=double(a);
for i=1:256;
    for j=1:256;
        b(i,j)=round(a(i,j)/2-0.5);
    end
end
subplot(231);
imshow(b,[]);
title('256*256,灰度級128');
%128*128,灰度級64
%a=double(a);
for i=1:256;
   for j=1:256;
       c1(i,j)=round(a(i,j)/4-0.5);
   end
end
for i=1:128;
    for j=1:128;
        c(i,j)=c1(2*i,2*j);
    end
end
subplot(232);
imshow(c,[]);
title('128*128,灰度級64');
%64*64,灰度級32
for i=1:256;
    for j=1:256;
        d1(i,j)=round(a(i,j)/8-0.5);
    end
end
for i=1:64;
    for j=1:64;
        d(i,j)=d1(4*i,4*j);
    end
end
subplot(233);
%subplot(233);
imshow(d,[]);
title('64*64,灰度級32');
%32*32,灰度級16
for i=1:256;
  for j=1:256;
        e1(i,j)=round(a(i,j)/16-0.5);
    end
end
for i=1:32;
    for j=1:32;
        e(i,j)=e1(8*i,8*j);
    end
end
subplot(234);
imshow(e,[]);
title('32*32,灰度級16');
%16*16,灰度級8
for i=1:256;
    for j=1:256;
        f1(i,j)=round(a(i,j)/32-0.5);
    end
end
for i=1:16;
    for j=1:16;
        f(i,j)=f1(16*i,16*j);
    end
end
subplot(235);
imshow(f,[]);
title('16*16,灰度級8');
%8*8,灰度級4
for i=1:256;
    for j=1:256;
        g1(i,j)=round(a(i,j)/64-0.5);
    end
end
for i=1:8;
    for j=1:8;
        g(i,j)=g1(32*i,32*j);
    end
end
subplot(236);
imshow(g,[]);
title('8*8,灰度級4');