Patent ID: 8824008

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 first set of three or more consecutive image correcting indexes of one direction and a second set of three or more consecutive image correcting indexes of another direction between reference marks of a first color, the first set and the second set of image correcting indexes being consecutively formed and comprising an identical second color 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 of an image correcting index located at the center of three 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 of the image correcting index located at the center of the three consecutive image correcting indexes, wherein the identical second color comprises a color other than black.