Detecting skew angle in a scanned image
First Claim
1. A method, comprising:
- generating a plurality of scanlines of grayscale image data that represent an original document captured inside a scan area;
interval sampling said captured grayscale image data to provide intensity values for corresponding pixels in said plurality of scanlines;
creating a two-dimensional array of relative intensity values for said plurality of scanlines, with relative intensity values for pixels from a same scanline arranged in a same array row and relative intensity values for pixels from a same sampling interval arranged in a same array column;
from said relative intensity values, identifying a plurality of background-to-medium transition points for said grayscale image data; and
determining a skew angle of said original document based upon a location of a plurality of said background-to-medium transition points.
1 Assignment
0 Petitions
Accused Products
Abstract
Detecting skew and determining skew angle using the front of a document by determining background-to-document transitions. Incoming scanlines are interval sampled in the fast scan direction every nth pixel. The samples are collected and organized into a two dimension array comprised of scanline based rows and interval based columns. The collected and organized samples are analyzed by intervals to determine a scanline (row) where a specified sampling condition exceeds predetermined threshold. The corresponding row-interval point forms a background-to-medium transition point of the edge of a document. When two or more background-to-medium transition points are found from different intervals the skew angle can be determined using linear regression.
-
Citations
20 Claims
-
1. A method, comprising:
-
generating a plurality of scanlines of grayscale image data that represent an original document captured inside a scan area;
interval sampling said captured grayscale image data to provide intensity values for corresponding pixels in said plurality of scanlines;
creating a two-dimensional array of relative intensity values for said plurality of scanlines, with relative intensity values for pixels from a same scanline arranged in a same array row and relative intensity values for pixels from a same sampling interval arranged in a same array column;
from said relative intensity values, identifying a plurality of background-to-medium transition points for said grayscale image data; and
determining a skew angle of said original document based upon a location of a plurality of said background-to-medium transition points. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A machine readable medium having instructions stored thereon that when executed by a processor cause a system to:
-
generate a plurality of scanlines of grayscale image data that represent an original document captured inside a scan area;
interval sample said captured grayscale image data to provide intensity values for corresponding pixels in said plurality of scanlines;
create a two-dimensional array of relative intensity values for said plurality of scanlines, with relative intensity values for pixels from a same scanline arranged in a same array row and relative intensity values for pixels from a same sampling interval arranged in a same array column;
from said relative intensity values, identify a plurality of background-to-medium transition points for said grayscale image data; and
determine a skew angle of said original document based upon a location of a plurality of said background-to-medium transition points. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. A system, comprising:
-
a document transport that moves an original document in a slow scan-direction to a scanning surface;
an image sensor that moves across said original document in a fast scan direction detecting the intensity of light reflected from said scanning surface and converts said reflected light into digital image data; and
a processor that interval samples said grayscale image data to provide intensity values for corresponding pixels in said plurality of scanlines, creates a two-dimensional array of relative intensity values for said plurality of scanlines identifies a plurality of background-to-medium transition points for said grayscale image data and determines a skew angle of said original document based upon a location of a plurality of said background-to-medium transition points. - View Dependent Claims (15, 16, 17, 18, 19, 20)
-
Specification