A method includes generating resolution images corresponding to the resolutions from each of a target image which is an image frame, included in a moving image or a still image group photographed continuously, of a processing target among the image frames and a processing target image photographed before the target image, executing block matching between a resolution image of the target image and a resolution image of the processing target image for each of the resolutions, calculating a plurality of motion vector candidates corresponding to the respective resolutions for each pixel of the target image, evaluating reliability of the plurality of motion vector candidates based on an evaluation index using noise characteristics related to pixel areas of a start point and an end point of each of the plurality of motion vector candidates for each pixel of the target image, and calculating a final motion vector.