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US Patent 6597813 - Masks with modulated clustering and aperiodicity and rescaling of masks
US Patent Issued on July 22, 2003
Estimated Patent Expiration Date:
March 11, 2019Estimated 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.
Estimated Patent Expiration Date:
March 11, 2019Estimated 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.AbstractA technique combines most of the advantages of both blue noise and clustering in generating a partially clustered aperiodic mask and using it in a dither array algorithm for halftoning, such that the amount of clustering can be modulated. A method to create an enlarged partially clustered aperiodic dither mask, appearing as a modulated version of a periodic enlargement of original mask, is used when the original mask generates patterns that are not visually pleasing or the original mask doesn't generate enough distinct grey levels. The method of halftoning of grey scale images utilizes a pixel-by-pixel comparison of the image against a partially clustered aperiodic mask in which the clustered aperiodic mask is comprised of a partly random and partly deterministic single valued function which is designed to produce visually pleasing dot configurations when thresholded at any level of grey. A method for changing a number of distinct grey levels a mask can produce to be used in halftoning of grey scale images produces advantages for some printing devices. | InventorsApplicationNo. 265861 filed on 03/11/1999US Classes:382/237, Gray level to binary coding358/3.16, Ordered dithering (e.g., deterministic or systematic)358/3.19, Stochastic or random dithering382/205Local neighborhood operations (e.g., 3x3 kernel, window, or matrix operator)Field of Search382/232, IMAGE COMPRESSION OR CODING382/237, Gray level to binary coding382/205, Local neighborhood operations (e.g., 3x3 kernel, window, or matrix operator)358/3.16, Ordered dithering (e.g., deterministic or systematic)358/3.17, Clustered pattern358/3.13, Dithering (e.g., spatial distribution of print elements by threshold matrix)358/3.2, Screen property or geometry (e.g., shape, period, symmetry, aspect ratio)358/3.19Stochastic or random ditheringExaminersPrimary: Coles, Edward L.Assistant: Mitchell, Monica Attorney, Agent or FirmUS Patent References5111310, Method and apparatus for halftone rendering of a gray scale image using a blue noise maskIssued on: 05/05/1992 Inventor: Parker, et al.5602943, Digital halftoning space filling curves Issued on: 02/11/1997 Inventor: Velho, et al.5917951Clustered aperiodic mask Issued on: 06/29/1999 Inventor: Thompson, et al. International ClassesG06K 009/36G06K 009/56 G06F 015/00 |
