IMAGE PROCESSING APPARATUS TO WHICH MOVING VECTOR SEARCH TECHNIQUE IS APPLICABLE, CONTROL METHOD THEREFOR, AND STORAGE MEDIUM STORING CONTROL PROGRAM THEREFOR

An image processing apparatus that is capable of improving image stabilization performance by improving motion vector search performance by restricting a search range even for an image with a large motion due to a camera shake of an image pickup apparatus at a tele-end side of a zoom lens or a shoot while walking at a wide-end side. A motion vector search unit searches for a motion vector of a reference image later input from an image pickup device with respect to a standard image input previously. A control unit sets at least one of a search range and a search position of a motion vector searched by the motion vector search unit based on position-posture change information about the image pickup apparatus detected by a detection unit and image stabilization control information obtained from an image stabilizing unit.