How can an RGB cell is filled in a particular region of an big image? (efficiently)

Sorry I asked this question before also, but still I am hoping if there is any better approach

I tried two methods but both are taking so much time.

1. zoomIm(2:5, 4:8, 1) = im(1, 1, 1);
   zoomIm(2:5, 4:8, 2) = im(1, 1, 2);
   zoomIm(2:5, 4:8, 3) = im(1, 1, 3);

2. zoomIm(2:5, 4:8, :) = repmat(im(1, 1, :), [5-2+1, 8-4+1, 1]);

Is it can be done something like below??

zoomIm(2:5, 4:8, :) = im(1, 1, :);