In the above-described embodiment, among the Voronoi seeds 44 of both the ends of the Voronoi sides 43, which intersect with the straight line 33, the Voronoi seeds 44 close from the intersection points 43a of the straight line 33 and the Voronoi sides 43 are identified as the centers of the empty circles. However, among the Voronoi seeds 44 of both the ends of the Voronoi sides 43, which intersect with the straight line 33, the Voronoi seeds 44 that are far from the intersection points 43a of the straight line 33 and the Voronoi sides 43 may be identified as the centers of the empty circles, or the Voronoi seeds 44 of both the ends of the Voronoi sides 43, which intersect with the straight line 33, may be identified as the centers of the empty circles.

While the image forming apparatus of the disclosure is the MFP in the embodiment, an image forming apparatus other than an MFP, such as a printer-only machine, may be applicable.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.