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:
Dec. 23, 1997
Filed:
Sep. 04, 1996
Victor Ostromoukhov, Lausanne, CH;
Smadar Nehab, Palo Alto, CA (US);
Canon Information Systems, Inc., Costa Mesa, CA (US);
Abstract
Halftoning gray scale image data includes selection of one of plural dither matrices based on an analysis of local tonality gradient for each target pixel. Plural different but reciprocally compatible dither matrices are defined, and for each target pixel in the gray scale image data, a local gradient for tonality is calculated. One of the dither matrices is selected in accordance with the calculated gradient, and the target pixel is thresholded using the selected dither matrix. Enhanced dithering according to the invention improves smoothness of gradations present in the invention, diminishes the 'banding' or 'contouring' effect found in natural images, and improves visual appearance and stability of business graphics, particularly in cases where a complex image contains both natural and computer generated business graphics.