The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 18, 1992
Filed:
Sep. 12, 1990
C S Chan, Bosie, ID (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A pixel assignment and error diffusion system and method for 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 the location of a just-scanned or just-processed super pixel 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. This developing gray scale profile and gradient of a scanned image is used to select a matching error diffusion set of diffusion points, each having a relative weight W and a location L, from a chosen look-up table stored in memory. The relative weight W is proportional to the gray level intensity of the developing profile and the location L is proportional to the slope of the gradient of a family of gray level profile or contour lines, wherein the gradient is generally perpendicular to these lines. The selected error diffusion set 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 within a larger scanned area.