  We consider a central extension of the mapping class group of a surface with
a collection of framed colored points. The Witten-Reshetikhin-Turaev TQFTs
associated to SU(2) and SO(3) induce linear representations of this group. We
show that the denominators of matrices which describe these representation over
a cyclotomic field can be restricted in many cases. In this way, we give a
proof of the known result that if the surface is a torus and there are no
colored points, the representations have finite image.
