EP0434415A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of measuring skew angles
Assignee: Xerox Corp
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Filing: 1990-12-20
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Granted: —
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Expires: 2010-12-20
Abstract
Abstract Skew angle of an image is determined based on determination of location of fiducial points on the image. Fiducial points may be located through a comparison of the scanning of a first line with scanning of a subsequent line. These fiducial points may be defined in terms of pixel color transitions located on a first scan line without a corresponding transition on the succeeding scan line. Skew angle may be determined from image data in uncompressed form or in compressed form. Where skew angle is determined from image data in compressed form, the two-dimensional CCITT facsimile recommendations may be used. In such cases, the locations of the fiducial points may be taken as the locations of the pass codes of the compressed image data. Specifically, pass codes indicating a pass of white pixels are used.
Inventors
- 👤 A. Lawrence Spitz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 10:41
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/70; G06T7/73; G06V; G06V30/00; G06V30/10; G06V30/14; G06V30/146; G06V30/1475; G06V30/1478
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
49 words
A method of operating a processor connected for accessing a data structure defining an image, the method comprising: accessing the data structure to obtain transition location data defining locations within the image of pixel color transitions and determining a skew angle of the image using the transition location data.
Claim 2
Dependent Claim
32 words
The method of claim 1, wherein the transition location data used to determine skew angle are transition location data corresponding to pixel color transitions from a black pixel to a white pixel.
Claim 3
Dependent Claim
20 words
The method of claim 1 or 2, wherein the the data structure defines the image in a compressed data format.
Claim 4
Dependent Claim
53 words
The method of claim 3, wherein the the data structure defines the image in a compressed data format according to the two-dimensional CCITT facsimile recommendations, and further comprising the steps of determining the locations of pass codes in the data structure, and selecting as transition location data the locations of the pass codes.
Claim 5
Independent Claim
124 words
A method for determining a skew angle of an image, wherein skew angle is determined as the angle corresponding to a selected one of a group of alignments, each alignment having associated with it a power upon which the selection is based, the power of each alignment being calculated from a count per line of selected features for that alignment, the image data being of the type which includes an indication of points of pixel color transition, comprising the steps of: selecting as features points of pixel color transition; selecting an alignment; determining the locations of the selected points of pixel color transition for the alignment, and calculating the power of the alignment from the locations of the selected points of pixel color transition.
Claim 6
Dependent Claim
102 words
A method as claimed in claim 5, including the steps of: selecting a first alignment; determining the locations of the selected points of pixel color transition for the first alignment; calculating the power of the first alignment from the locations of the selected points of pixel color transition; selecting a second alignment; determining the locations of the selected points of pixel color transition for the second alignment; calculating the power of the second alignment from the locations of the selected points of pixel color transition, and determining the skew angle from a comparison of the powers of the first and second alignments.
Claim 7
Dependent Claim
50 words
The method of claim 6, wherein the image data are in a compressed format which includes pass codes, and further including the steps of determining the locations of those pass codes, and utilizing the locations of those pass codes as the locations of the selected points of pixel color transition.
Claim 8
Dependent Claim
21 words
The method of claim 7, including the further step of using those pass codes that indicate a pass of white pixels.
Claim 9
Independent Claim
89 words
A method for determining skew angle or angles of a scanned image, wherein skew is determined by forming a count of selected topographic features of the image, forming selected weighted sums of the selected topographic features such that the topographic features form a plurality of alignments, and determining as the skew angle or angles that alignment or alignments which maximize one or more of the weighted sums, including the steps of: selecting a plurality of points located on the image, and using the selected points as the topographic features.
Claim 10
Dependent Claim
20 words
The method of claim 9, wherein the plurality of selected points on the image are line ends of the image.
References Cited (Backward Citations)
No citation records indexed.
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