1. A method for pixel value interpolation of a current frame in an image system, the method comprising: applying a motion compensation filter for fractional motion vector displacement on integer pixel points of a reference frame to determine a value for a fractional point, the motion compensation filter including a positive lobe between two negative lobes, wherein the reference frame is further distant than another referenceable frame in display order to the current frame; receiving a signal identifying the another referenceable frame as expired; and in response to the signal, discarding the another referenceable frame as a referenceable frame.