Color bitmap generation with background dependent black objects

Abstract

A bitmap-based digital color printing method and system is described which automatically detects when a black object is commanded to be printed, and changes the Bit Block Transfer (BitBlt) method so that the resultant composition of the black color at each point in the bitmap is responsive to the amount of non-black colorants already existing in the background color at that position on the page. For many printing systems the resulting prints exhibit fewer visual defects. Single-color black objects printed on top of a color field are printed as process black responsive to the background color. Therefore, they exhibit a greater density and gloss and show fewer problems caused by the misregistration of separations or other printer defects, such as white fringes around the black objects. They also avoid problems caused by excessive ink coverage differences between foreground black and background color. Conversely, process black objects not on a color background may be printed as single-color black objects and therefore do not exhibit objectionable process black problems such as color fringing, excessive colorant, and excessive gloss contrast with the background.

Dependencies are inferred from the claim text.