Multi-resolution images of a reference image and a target image are generated. Then, whole-range matching is performed on an image of a lower resolution to detect a two-dimensional displacement between the images. Block matching is performed on an image of a higher resolution to detect a displacement at each feature point. The accuracy of motion data is increased by correcting the motion data with an image of a higher resolution by using the previously calculated motion data of the lowest resolution through higher resolutions as an initial value.