1. An image forming apparatus comprising: an image information acquisition unit that acquires image information; a toner image formation unit that forms, in response to a control parameter, a toner image on a surface of an image carrier based on the image information acquired by the image information acquisition unit; an image density detection unit that produces a detection result indicative of image density of the toner image formed on the surface of the image carrier; and a control unit that performs a determination processing for determining whether to use a predetermined region in the toner image formed on the surface of the image carrier based on the image information for a detection of the image density of the toner image in a parameter correction processing, and when the predetermined region is determined to be used for the detection of the image density in the determination processing, performs the parameter correction processing for correcting the control parameter used by the toner image formation unit based on the detection result so as to maintain the image density in the predetermined region within a predetermined range.