1. An image forming apparatus, comprising: an image information acquisition circuit that acquires image information; a toner image formation circuit 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 circuit; a control circuit that determines, based on the image information, whether to use a predetermined region for a detection of an image density of the toner image in a parameter correction processing, the predetermined region being a segment of the toner image formed on the surface of the image carrier; and an image density detection circuit that, when the control circuit determines to use the predetermined region for the detection of the image density, detects the image density of the toner image formed on the surface of the image carrier and produces a detection result according to the detected image density, wherein the control circuit further performs the parameter correction processing, when the predetermined region is determined to be used for the detection of the image density, to correct the control parameter used by the toner image formation circuit according to the detection result so as to maintain the image density in the predetermined region within a predetermined range.