Maybe something like this
a = [1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 1 1 0 0]
b = repelem(any(reshape(a,4,[]),1),4)
I'm assuming the input is nominally binarized already (i.e. either logical class or numeric class but integer-valued and constrained to [0 1]). If otherwise, you'll have to explicitly convert it to logical using some desired test.
If the output needs to be numeric class, cast it using double().
