Patent ID: 7522308

Claim:
A method of detecting color deviation in a color image forming apparatus which forms a color image on an image-formation medium by superposing monocolor images each provided by each of plurality of colors, the method comprising: obtaining basic color information including at least one of (A) color information of at least one of a first-color basic image provided by one of two colors of the plurality of colors, a second-color basic image provided by the other of the two colors, and a superposed-color basic image formed by superposing monocolor images each provided by each of the two colors, each of the first-color basic image, the second-color basic image, and the superposed-color basic image being a basic image which is formed by the color image forming apparatus and from which is obtained information that is a basis for detecting the color deviation, and (B) color information of the image-formation medium which is not colored by any of the two colors; obtaining superposed-pattern color information which is color information of a pattern-superposed image formed by the color image forming apparatus such that two pattern images each provided by each of the two colors are superposed; and detecting a relative positional deviation between the two pattern images, on the basis of the basic color information and the superposed-pattern color information.