Patent ID: 8570594

Claim:
An image forming apparatus in which image forming units each having an image carrier, an exposure unit for exposing by drawing a scanning line on the image carrier with a beam, and a developing unit for visualizing an electrostatic latent image generated by the exposing using a color former are juxtaposed in a conveying direction of a print medium, comprising: a memory; an image storage unit configured to store an image including a plurality of pixels to the memory; a selecting unit configured to select a rotational speed of an image carrier from among a plurality of rotational speeds of a image carrier; a setting unit configured to set a size of a print medium; a shifting amount storage unit configured to store information indicating a shifting amount in a sub-scanning direction of a pixel on the scanning line drawn on the image carrier with the beam from an ideal scanning line; a calculation unit configured to calculate a correction amount in a sub-scanning direction of a pixel included in the stored image on the basis of the selected rotational speed, the set size of a print medium and the stored information, wherein the more the selected rotational speed, the greater a correction amount in a sub-scanning direction of a pixel included in the stored image is; a conversion unit configured to convert a read position in the stored image according to the calculated correction amount; and a read out unit configured to read out a pixel of the converted read position from among the image stored in the memory.