Method and system for printing in one or more color planes with improved control of error diffusion

摘要

A pixel assignment and error diffusion system and method of gray scale printing in one or more color planes in the fields of ink jet printing, electrophotographic printing, or the like. The direction of each error diffusion with respect to (28) the location of a just-scanned or just-processed super pixel (28) within a larger scanned area is controlled by the contemporaneously developing gray scale profile and gradient over a previously scanned area defined by a predetermined number of previously scanned super pixels (28-44). This developing gray scale (116, 118, 120, 122) profile and gradient of a scanned image is used to select a matching error diffusion set (E) of diffusion points, each having a relative weight W and a location L, from a chosen look-up table stored in memory (98). The relative weight W is proportional to the gray level intensity of the developing profile (116, 118, 120, 122) and the location L is proportional to the slope of the gradient of a family of gray level profile or contour lines (104, 108, 112), wherein the gradient is generally perpendicular to these lines. The selected error diffusion set (E) is in turn used to control the direction and weighted distribution of an error remainder value R into areas of a processed image adjacent each just-scanned or just-processed super pixel (28-44) within a larger scanned area.