Image forming apparatus having banding correction function

An image forming apparatus including an image forming unit having a rotary member for image formation based on image data that is externally input, the image forming apparatus comprising:

• a correction section that performs banding correction for banding periodically occurring in a sub-scanning direction, by correcting the image data based on banding correction information according to a phase of the rotary member;
• a control section that performs control to make the image forming unit form an inspection image for determining whether or not an intensity of the banding periodically occurring in the sub-scanning direction is suppressed to be smaller than a predetermined threshold value, for an image formed by the image forming unit;
• and
• a detection section that detects the intensity of the periodic banding in the sub-scanning direction of the inspection image formed by the image forming unit,
• wherein if based on the intensity of the banding detected by the detection section, the control section has determined that the banding is not suppressed to be smaller than the predetermined threshold value, the control section performs control to not perform the banding correction or performs control to re-set a relationship between the phase of the rotary member and the banding correction information for correcting the image data.