Manual threshold_ What is wrong?

img = imread('cameraman.tif');
%Threshold the image at the intensity level 128
%make all the values in the image less than 128 to 0 and equal or greater than 128 to 255

imgT = img;

[M N]=size(img);
for i=1:M
    for j=1:N
        if (img(i,j)==128 || img(i,j)>128)
            imgT(i,j)=1;
        else
            imgT(i,j)=0;
        end
    end
end
figure;
subplot(1,2,1)
imshow(img)
subplot(1,2,2)
imshow(imgT, [])
imgT=uint8(imgT);