US 5,528,387 AGranted

Electronic image registration for a scanner

AssigneeXerox Corporation

InventorsNancy R. Kelly, Thomas I. Yeh

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Abstract

A system electronically registers an image on an input document. The system includes a scanner for generating an image data stream representing an electronic image of the image on the input document and an edge detecting circuit for detecting edge data within the image data stream. A circuit calculates a skew angle of the input document based on the detected edge data and rotates the electronic image based on the calculated skew angle to register the electronic image with an output medium. The system also includes a non-image area generating circuit for generating areas in the electronic image which correspond to non-image areas based on the calculated skew and detected edge data. The skew calculation, rotation operation and the non-image area generation is based the electronic detection of the corners and center of the leading edge of the document being scanned.

Claims17

Dependent claims

A system for electronically registering an image on an input document, comprising:

scanning means for generating an image data stream representing an electronic image of the image on the input document;
edge detecting means, operatively connected to said scanning means, for detecting edge data within the image data stream;
first corner detecting means, operatively connected to said edge detecting means, for detecting a first corner of a leading edge of the input document based on the detected edge data and for establishing a first coordinate value therefrom;
center detecting means, operatively connected to said edge detecting means, for detecting a center of a leading edge of the input document based on the detected edge data and for establishing a second coordinate value therefrom;
second corner detecting means, operatively connected to said edge detecting means, for detecting a second corner of a leading edge of the input document based on the detected edge data and for establishing a third coordinate value therefrom;
skew means for calculating a skew angle of the input document based on the first, second, and third coordinate values;
and
rotation means for rotating the electronic image based on the calculated skew angle to register the electronic image with an output medium.

5 more elements

A method for electronically registering an image on an input document, comprising the steps:

(a) generating an image data stream representing an electronic image of the image on the input document;
(b) detecting edge data within the image data stream;
(c) detecting a first corner of a leading edge of the input document based on the detected edge data;
(d) establishing a first coordinate value based on the detected first corner;
(e) detecting a center of a leading edge of the input document based on the detected edge data;
(f) establishing a second coordinate value based on the detected center;
(g) detecting a second corner of a leading edge of the input document based on the detected edge data;
(h) establishing a third coordinate value based on the detected second corner;
(i) calculating a skew angle of the input document based on the detected first and second corners and the detected center of the leading edge of the input document;
and
(j) rotating the electronic image based on the calculated skew angle to register the electronic image with an output medium.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/344,051Filed 23 Nov 1994
Granted: 18 Jun 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

H04N 1/3878
Image rotation: skew detection or correction
G06T 3/403
Scaling of whole images or parts thereof, e.g. expanding or contracting: edge-driven scaling; Edge-based scaling
G06T 3/608
Rotation of whole images or parts thereof: by skew deformation, e.g. two-pass or three-pass rotation
G06V 30/1475
Aligning or centring of the image pick-up or image-field: inclination or skew detection or correction of characters or of image to be recognised