Image forming apparatus

An image forming apparatus comprising:

• an image former configured to form an image quality adjustment pattern image on an image carrier to be driven at a predetermined speed;
• a detector configured to detect the image quality adjustment pattern image;
• an image quality adjustment controller configured to control image quality adjustment processing in accordance with a detection result by the detector;
• a speed changer configured to change an image formation speed indicating a speed at which an image is formed;
• a size changer configured to change a size of the image quality adjustment pattern image in a sub-scanning direction in accordance with a change amount between the image formation speed before being changed by the speed changer and the image formation speed after being changed by the speed changer;
• and
• an interval changer configured to change, when the speed changer changes the image formation speed and while the image carrier is driven at the predetermined speed, an interval at which the detector acquires the detection result in accordance with the change amount between the image formation speed before being changed by the speed changer and the image formation speed after being changed by the speed changer.