Patent ID: 8830521

Claim:
An image forming apparatus comprising: an image forming unit that forms an image by using a plurality of predetermined colors; an index forming unit that causes the image forming unit to form a plurality of image correcting indexes comprising a plurality of color position control marks disposed alternately with black position control marks, at least one of color position control marks comprising two or more consecutive portions of one orientation, the image correcting indexes being used for correcting misregistration of an image to be formed by the image forming unit; an image carrier onto which the image correcting indexes formed by the image forming unit are sequentially transferred; a detector including a light source that emits light to the image correcting indexes and a light receiver that receives light reflected by the image carrier and the image correcting indexes so as to generate a detection signal for detecting the image correcting indexes; a position specifying unit that specifies a position between two consecutive image correcting indexes by using the detection signal obtained from the light receiver of the detector; and a misregistration correcting unit that corrects misregistration of an image to be formed by the image forming unit by using the specified position between the two consecutive image correcting indexes, wherein each of the image correcting indices comprises a first side and a second side consecutively formed obliquely to the first side in both a first direction and a second direction perpendicular to the first direction, wherein the at least one color position control mark comprises two first sides and two second sides of a same color, and wherein a direction of the two first sides is opposite to a direction of the two second sides.