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1  I=imread("cameraman.tif");
[m,n]=size(I);
J_128=zeros(m/2,n/2);
for i=1:m/2
    for j=1:n/2
        J_128(i,j)=I(2*i,2*j);
    end
end
J_64=zeros(m/4,n/4);
for i=1:m/4
    for j=1:n/4
        J_64(i,j)=I(4*i,4*j);
    end
end
J_32=zeros(m/8,n/8);
for i=1:m/8
    for j=1:n/8
        J_32(i,j)=I(8*i,8*j);
    end
end
figure;
subplot(2,2,1);
imshow(I);
title('original img');

subplot(2,2,2);
imshow(J_128,[]);
title('img 128 bit');


subplot(2,2,3);
imshow(J_64,[]);
title('img 64 bit');


subplot(2,2,4);
imshow(J_32,[]);
title('img 32 bit');


2 I = imread("peppers.png")
[m,n,c]=size(I);
J=zeros(m,n );
J1=zeros(m,n );

for i = 1:m 
   for j = 1:n 
        J(i,j)=(I(i,j,1)+I(i,j,2)+I(i,j,3))/3;
    J1(i,j)=(0.299*I(i,j,1)+0.587*I(i,j,2)+0.114*I(i,j,3))/3;
   end;
end;
figure;
subplot(2,2,1);
imshow(I);
title("Original");
subplot(2,2,2);
imshow(J,[]);
title("grey");
subplot(2,2,3);
imshow(J1,[]);
title("grey");