1. An image processing method for use with an image processing apparatus for processing an input image, the image processing method comprising the steps of: detecting a motion vector at each of a plurality of space position within a predetermined range including a subject space position that is a space position of interest, of a frame at a predetermined time from an input image of a plurality of temporally different frames and obtaining a reliability of the motion vector; obtaining, at each of the plurality of space positions, an evaluation value of the motion vector at the space position, on the basis of the reliability of the motion vector at the space position and a weighting corresponding to a distance from the subject space position; and correcting the motion vector at the subject space position on the basis of the evaluation values and the motion vectors at the plurality of space positions of the predetermined range, wherein the weightings of the space positions on one side of the subject space position is set to 0 when space positions on the other side of the subject space position has corresponding reliabilities that are higher than the reliabilities corresponding to the space positions of the one side.