JP2992065B

PURPOSE:To reduce the arithmetic quantity by calculating a picture element correlation value between a retrieval reference point and its adjacent point, selecting a point having a maximum correlation as a succeeding retrieval reference point and outputting a tracing command when a correlation value of the new retrieval reference point has a value higher than the correlation of the adjacent point. CONSTITUTION:A correlation arithmetic section 4 obtains a correlation g0(x0, y0) between a real picture and a reference picture as to a retrieval reference point for each picture element and obtains correlation values g1(x1, y1) to g4(x4, y4) between a real picture and a reference picture at a point adjacent to the retrieval reference point and retrieves a point having the largest correlation and applies correlation retrieval by using the point having the largest correlation as a succeeding retrieval reference point. Thus, the retrieval reference points are sequentially retrieved and when the correlation g0(x0, y0) at the retrieval reference point is larger than any of the correlation values g1(x1, y1) to g4(x4, y4) at the adjacent points, the correlation arithmetic section 4 gives a command tracing to the object position in a frame picture at this time to the picture sensor 1. Thus, the arithmetic quantity is considerably reduced.