An image processing apparatus includes: a controller that causes an image forming unit to form an image so that a plurality of unit images are arranged in a first direction with a constant distance between adjacent unit images; an acquisition unit that acquires read image data indicating a position and a grey level value of each pixel constituting the image formed under control of the controller; and a calculation unit that calculates a misregistration with respect to the first direction of the image formed by the image forming unit, based on a convolution operation performed on the read image data acquired by the acquisition unit, the convolution operation using a reference periodic function whose variable is a position in the first direction.