Patent ID: 8428483

Claim:
An image forming apparatus which forms a test pattern including a belt-shaped pattern, the image forming apparatus comprising: an image forming section which forms the belt-shaped pattern on a sheet, the belt-shaped pattern which has a prescribed length extending in a main-scanning direction, and of which a density is measured at prescribed measurement-distance intervals starting from a measurement starting position corresponding to a formation starting position of the belt-shaped pattern; and a control section which allows the image forming section to form the belt-shaped pattern on a plurality of sheets in such a way that the formation starting position of the belt-shaped pattern is shifted for a distance in the main-scanning direction sheet by sheet, the distance which is obtained by dividing the measurement-distance by a number of sheets on which the belt-shaped pattern is to be formed; collects a plurality of pieces of density information sheet by sheet, the pieces of density information each of which indicates the density of the belt-shaped pattern at a measurement position of a plurality of measurement positions; creates data in which the collected pieces of density information respectively correspond to the measurement positions arranged in the main-scanning direction on each of the sheets; and corrects density unevenness of image data in the main-scanning direction based on the created data, wherein the image forming section forms an image on a sheet based on the image data of which the density unevenness is corrected.