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D = eye(100,100);
C = logical(D);
BI2 = [1 1 1 1; 1 0 0 0; 1 1 1 1; 1 0 0 1; 1 1 1 1; 0 0 0 0];
BI = logical(BI2);
whos BI
whos BI2

C(10:15, 2:5) = BI;
subplot(221)
imshow(C)
subplot(222)
imshow(rot90(C.'));
subplot(223);
imshow(C(0:100:4, 0:100:4))

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