  The effect of filtering operation with respect to purification and
concentration of entanglement in quantum states are discussed in this paper. It
is shown, through examples, that the local action of the filtering operator on
a part of the composite quantum state allows for purification of the remaining
part of the state. The redistribution of entanglement in the subsystems of a
noise affected state is shown to be due to the action of local filtering on the
non-decohering part of the system. The varying effects of the filtering
parameter, on the entanglement transfer between the subsystems, depending on
the choice of the initial quantum state is illustrated.
