an image input device inputting image sequence data;

a memory storing a first image and a second image as the image sequence data;

a tracking point indication unit configured to initially indicate a plurality of tracking points on the first image stored in said memory;

a pattern matching unit configured to compare a pattern of each tracking point of the first image with the second image stored in said memory, and to detect a plurality of destination candidate points from the second image, wherein each of the destination candidate points corresponds to each of the tracking points; and

a position inconsistency correction unit configured to link each tracking point with a plurality of segments so that none of the plurality of segments intersect, to analyze a positional relationship between each side and each vertex of each triangle formed by neighboring three of the segments of each tracking point, to link each destination candidate point with a plurality of segments so that none of the plurality of segments intersect, to analyze a positional relationship between each side and each vertex of each triangle formed by neighboring three of the segments of each destination candidate point, to decide whether a positional relationship of the plurality of destination candidate points is consistent with a positional relationship of the plurality of tracking points, and to correct at least one of the plurality of destination candidate points on the second image by using the positional relationship of the plurality of tracking points if the positional relationship of the plurality of destination candidate points is inconsistent with the positional relationship of the plurality of tracking points because of the at least one of the plurality of destination candidate points.