Patent ID: 6888645

Claim:
A color image forming apparatus comprising: a first image processing unit and a second image processing unit, each having, a photosensitive body, exposing means for forming an electrostatic latent image by exposing a surface of said photosensitive body, and a plurality of developing devices for supplying said electrostatic latent image with toner, each of said plurality of developing devices withholding toner of a different color provided that one of said developing devices in said first image processing unit withholds black toner, a color image being formed by transferring toner images formed on said photosensitive bodies in said first and second image processing units so as to be superimposed over one another, additional information composite means for producing a composite image by combining a chief monochrome image with additional information, said additional information forming an image different from said chief monochrome image, and control means for having a first image processing unit form said chief monochrome image and said second image processing unit form the image of said additional information, said chief monochrome image and said image of said additional information being formed simultaneously when said chief monochrome image is to be combined with said image of said additional information in a color other than black to produce a composite image.