An image processing method for a video processor, for generating an extrapolated frame according to a previous frame and a current frame, includes steps of: projecting a plurality of motion vectors (MVs) to the extrapolated frame subsequent to the current frame; determining whether a block of the extrapolated frame is projected by at least two of the MVs; selecting at least two candidate MVs from the MVs projected to the block when the block is projected by at least two of the MVs; calculating a blended MV which is a mixture of the at least two candidate MVs, and projecting the blended MV to the previous frame; obtaining a reference MV corresponding to position of the previous frame projected by the blended MV; and comparing the reference MV with the at least two candidate MVs, to select a final MV for the block from the at least two candidate MVs.