Partial differentiations relative to x and y are obtained by termwise differentiating the mutual correlation coefficient R(x, y), and (x, y) at which the mutual correlation coefficient R(x, y) becomes a maximal value is obtained from repeated operations by using the partial differentiations and used as coordinates of the tie point. そして、相互相関係数R(x,y)を項別微分することによってx、yについての偏微分を得、相互相関係数R(x,y)が極大値となる(x,y)をそれらの偏微分を利用した反復演算から求めてタイポイントの座標とする。 - 特許庁