Error diffusion of subcells in digital halftoning
May 21, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesTone error control for relatively large image areas Picture processing method Multiple mode binary image processing Method for rendering gray scale images with variable dot sizes Method of displaying continuous tone picture using limited number of different colors or black-and-white levels, and display system therefor Process for recording semihalftone images Bi-level image display signal processing apparatus Patent #: 4891710 InventorApplicationNo. 525583 filed on 05/21/1990US Classes:358/3.03, Error diffusion in gray level or halftone generation358/466Variable thresholding techniqueExaminersPrimary: Shoop, William M. Jr.Assistant: Moskowitz, Larry Attorney, Agent or FirmInternational ClassH04N 001/40AbstractA system for converting gray-level input data into binary output data and efficiently preserve much of the original sharpness information. The input data is divided into halftone cells which correspond to several pixels in the original image information. The halftone cells are further divided into subcells which correspond to a plurality of pixels in the halftone cell. The subcells are thresholded with a matrix of threshold values to determine which binary pixels are to be rendered. Any error between the rendered pixels and the average density value of the subcell input values is propagated to adjacent subcells. The thresholding of the subcell pixels can use a separate threshold value for the individual pixels or can use an average threshold value for the entire subcell. | |
