1. An information processing apparatus comprising: a detection unit that detects, as edge pixels, a plurality of pixels in a contour of a head of a person in an image in which the head appears; a determination unit that, for each of the edge pixels, determines, as ellipse candidates, a plurality of ellipses that pass through the edge pixel in a parameter section including predetermined parameters that define an ellipse; a calculation unit that, for each of the edge pixels, calculates an evaluation value based on, for each of the ellipse candidates determined for the edge pixel, a position of the edge pixel in the ellipse candidate; an accumulation unit that accumulates the evaluation values for each of the ellipse candidates; and a selection unit that selects an ellipse candidate having the highest accumulated evaluation value from the ellipse candidates as the head ellipse.