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:
Jun. 03, 1986
Filed:
Aug. 20, 1984
Henry N Kannapell, Raleigh, NC (US);
Thomas W Bobick, Richardson, TX (US);
The Mead Corporation, Dayton, OH (US);
Abstract
An adaptive threshold for processing grayscale image data obtained by scanning a document to be duplicated is set by initially dividing the data into data groups representative of selected pixels of the document. A background grayscale value and a print grayscale value are determined for each data group with the difference between the two defining a contrast grayscale value. An estimated threshold is calculated by adding 0.4 of the contrast to the background. An average threshold is also determined for the area of each data group by averaging the thresholds for contiguous data groups for which thresholds have been established. The adaptive threshold is determined for each data group by setting the adaptive threshold to the average threshold +1 if the estimated threshold exceeds the average threshold; to the average threshold -1 if the estimated threshold is less than the average threshold; and, to the average threshold otherwise. The grayscale image data for each data group is compared to its corresponding adaptive threshold to generate binary data which drives a printer to substantially duplicate the document.