Patent ID: 8035856

Claim:
An image forming apparatus for forming a tone image using a density pattern method, comprising: an image forming unit configured to form an image by an electrophotographic method; a first storage unit configured to store a density pattern corresponding to each tone and an ideal density value of the density pattern in correspondence with each other; a density detection unit configured to detect an optical density of an image that has been formed by the image forming unit; a second storage unit configured to store optical densities, detected by the density detection unit, of images formed by the image forming unit in accordance with density patterns corresponding to respective tones, in correspondence with the respective tones, and a modification unit configured to cause the image forming unit to form an image based on a density pattern corresponding to each tone and modify the density pattern corresponding to the each tone, which has been stored in the first storage unit, based upon the optical density detected by the density detection unit and the ideal density value corresponding to the density pattern; wherein if a first ideal density value corresponding to a first tone stored in the first storage unit and any one of the optical densities stored in the second storage unit match or differ by less than a prescribed amount, then the modification unit replaces a first density pattern corresponding to the first tone in the first storage unit with the density pattern corresponding to the one of the optical densities.