1. An image processing apparatus that generates an image data used in printing an image on a sheet being attachable to skin, the image processing apparatus comprising: an image acquirer that acquires a skin image picked up from the skin; an image analyzer that extracts, from the skin image, a discolored region differing in color from surrounding skin by at least a predetermined level, and surrounding color being color of the skin surrounding the discolored region; a grouping processor that groups a plurality of the discolored regions, and determines an inclusive region for each region group which is a cluster of the grouped plurality of discolored regions or the one discolored region not having been grouped, to include the one or a plurality of the region groups; and a printing controller that generates the image data having a content of printing a pigment material that causes color of the inclusive region to approximate the surrounding color, on a region corresponding to the inclusive region in the sheet.