A graphics processing system includes a processing circuit operable to render or decode a sequence of frames and generate extrapolated frames by extrapolating object motion from rendered or decoded frames. The system also includes a processing circuit operable to extrapolate object motion from first and second rendered or decoded frames in the sequence to a later extrapolated frame. The processing circuit is also operable to test candidate motion vectors from a region of the extrapolated frame through a region of the first frame to a region of the second frame by comparing the region of the first frame with the region of the second frame. A similarity measure from the comparison is used to select a motion vector and an indication representative of the selected motion vector is stored.