1. An information processing apparatus that generates a rectangular image into which a 3D scene is rendered for a predetermined viewpoint, the apparatus comprising: an obtainer which is able to obtain a number of fragments existing on a straight line defined by the viewpoint and a predetermined point within the 3D scene to be rendered for each pixel of the rectangular image; a divider which is able to divide a two-dimensional region in a screen coordinate system corresponding to the rectangular image into a plurality of regions; and a calculator which is able to perform a predetermined calculation where each of the plurality of regions is taken as one unit of calculation, wherein said divider divides the two-dimensional region into the plurality of regions by one or more dividing line so that a difference of summations of the number of fragments included in each of the regions after the division becomes a minimum.