Facsimile and static presentation processing – Facsimile – Picture signal generator
Patent
1997-12-05
1999-12-21
Nguyen, Madeleine
Facsimile and static presentation processing
Facsimile
Picture signal generator
358449, 358520, 395117, 382286, H04N 104, H04N 140, G06K 936
Patent
active
060056835
ABSTRACT:
A technique for document edge detection in an optical scanning system. The document is placed against an over-sized neutral background. A linear optical sensor array is used to provide successive lines of pixel data representing the luminance of detected pixel areas. Commencing from one end of the line of pixel data, for successive current pixels being tested, a group of n adjacent pixel values is correlated with a successive group of n adjacent pixel values to provide a correlation value for the current pixel. One of the groups is assumed to contain only background pixels, and their luminance is approximated to be equal to the average luminance over the entire background. If the correlation value exceeds a threshold constant, the current pixel is chosen to be an edge in this line of pixels. Data from several lines is processed to find corresponding edges for each line, and the line edges are subjected to a least squares fit to calculate the location of the document edge. The left and right edge of the document can be found using this technique. A histogram of luminance values for each line of pixel data is analyzed to determine whether an edge value is valid.
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Son Myungsae
Weldon John M.
Hewlett--Packard Company
Nguyen Madeleine
Potts Jerry R.
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