1. An apparatus comprising: a correcting component configured to correct grey levels of the upper and lower side edges in the subscanning direction of an image to be printed; an output component configured to output a plurality of images to a printing component, wherein gray levels of a middle area in the subscanning direction in the plurality of images are common among the images, gray levels of one side edge in the subscanning direction in the plurality of images are different among the images and each gray level of the one side edge is thinner than those of the middle area, and gray levels of the other side edge in the subscanning direction in the plurality of the images are different among the images and each gray level of the other side edge is thicker than those of the middle area; and an input component configured to input information from an operator of a) one of upper side edges among a plurality of upper side edges of the plurality of images and b) one of lower side edges among a plurality of lower side edges of the plurality of images, after the plurality of images are printed by the printing component, wherein the correcting component corrects the grey levels of the upper and lower side edges in the subscanning direction of the image to be printed based on the input information.