Multi-bit rendering with single color and two-color capability

Abstract

In an electrostatographic recording apparatus and method of forming images on a charge retentive surface such as a photoconductive member using a single writer source, the surface is uniformly charged by a corona charger to a predetermined voltage potential level. An image frame is then exposed on a pixel by pixel basis with varying amounts of exposure by the source for at least some pixels to form a tri-state type of latent image on the image frame including a charged area developable (CAD) latent image having at least some exposed pixels at various different sub-levels of exposure within the CAD latent image, a discharged-area developable (DAD) latent image having at least some exposed pixels at various different sub-levels of exposure within said discharged area developable image, and a background area The DAD and CAD latent images are then developed with toners of two different colors by two different developer sources. A second image frame of the uniformly charged surface is also exposed on a pixel by pixel basis with varying amounts of exposure by the source for at least some pixels to form a monochrome latent image wherein at least some exposed pixels are exposed at various different levels of exposure. The monochrome latent image is developed using one of the developer sources and this source is biased differently on the monochrome exposure made from the bias used in the two-color exposure mode. Data representing multicolor pixels are analyzed in accordance with criteria and a determination is made as to whether the pixel is to be recorded in black or another color in the tri-state recording mode.