Patent ID: 7344217

Claim:
An image forming apparatus having an image forming unit which includes an image carrier, an exposure unit used to expose the image carrier, and a developing unit used to visualize an electrostatic latent image generated by exposure using a printing medium, comprising: a shifting amount of color storage unit adapted to store information of shifting amount of color that represents a shifting amount of color of an exposure position in a sub-scan direction upon exposing the image carrier while scanning the image carrier in a main scan direction; a shifting amount of color compensation amount calculator adapted to calculate a shifting amount of color compensation amount required to compensate the shifting amount of color in the sub-scan direction based on the shifting amount of color; an image data storage unit adapted to store image data formed by a plurality of pixels; an address converter adapted to convert a coordinate of a read address of said image data storage unit based on a shifting amount of color in a pixel unit of the shifting amount of color compensation amount, and to read out pixel data of a pixel of interest from said image data storage unit in accordance with the converted address information; a pixel color density converter adapted to convert a pixel color density of the pixel data read out from said image data storage unit by said address converter based on a shifting amount of color less than a pixel unit of the shifting amount of color compensation amount; a half-tone processing unit adapted to perform half-tone processing of the pixel data which has undergone the color density conversion by said pixel color density converter; an exceptional processing unit adapted to perform exceptional processing of the pixel data which has undergone the color density conversion by said pixel color density converter; a process determination unit adapted to detect a feature of image data formed by pixels in a predetermined region having the pixel of interest as a center of the image data stored in said image data storage unit, and to determine one of the exceptional processing and the half-tone processing to be selected; and an output unit adapted to select a processing result of one of said exceptional processing unit and said half-tone processing unit based on a determination result of said process determination unit, and to output the selected processing result as an exposure control signal of the exposure unit.