Patent US1001664A successfully refreshed from Google Patents.
Patent US5054094A successfully refreshed from Google Patents.
US5054094A
Expired / Lapsed
US
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Rotationally impervious feature extraction for optical character recognition
Assignee: Eastman Kodak Co
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Filing: 1990-05-07
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Granted: 1991-10-01
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Expires: 2010-05-07
Abstract
Abstract A feature-based optical character recognition system, employing a feature-based recognition device such as a neural network or an absolute distance measure device, extracts a set of features from segmented character images in a document, at least some of the extracted features being at least nearly impervious to rotation or skew of the document image, so as to enhance the reliability of the system. One rotationally invariant feature extracted by the system is the number of intercepts between boundary transitions in the image with at least a selected one of a plurality of radii centered at the centroid of the character in the image.
Inventors
- 👤 Lori L. Barski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:30
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/10; G06V30/18
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
126 words
A feature-based optical character recognition system for extracting features from an individual character image segmented from a document image, comprising: radial intercept feature extraction means for counting a number of intercepts between at least one of a plurality of circles of predetermined radii and boundary transitions in said character image; transition point location feature extraction means for determining for each transition point in said image an identity of a pair of regions in a grid superimposed on said character image nearest the transition point, whereby said number of intercepts and said identity of said pair of regions comprise an input data string; and feature-based recognition means for comparing said input data string with a set of reference data strings corresponding to a set of known symbols.
Claim 2
Dependent Claim
126 words
A feature-based optical character recognition system for extracting features from an individual character image segmented from a document image, comprising: radial intercept feature extraction means for counting a number of intercepts between at least one of a plurality of circles of predetermined radii and boundary transitions in said character image; transition point location feature extraction means for determining for each transition point in said image an identity of a pair of regions in a grid superimposed on said character image nearest the transition point, whereby said number of intercepts and said identity of said pair of regions comprise an input data string; and feature-based recognition means for comparing said input data string with a set of reference data strings corresponding to a set of known symbols.
Claim 3
Dependent Claim
42 words
The system of claim 1 wherein said radial intercept feature extraction means comprise: means for locating a centroid and boundary of an object in said character image; means for selecting one radius of said circle and centering said circle at said centroid.
Claim 4
Dependent Claim
59 words
The system of claim 2 wherein said means for selecting said radius comprise: means for locating with respect to said centroid a reference radius between a minimum radial peak and a maximum radial valley in said boundary; and means for computing said one radius as a weighted average of said reference radius and a mean radius of said boundary.
Claim 5
Dependent Claim
65 words
The system of claim 2 wherein said radial intercept feature extraction means further comprises: means for determining for each one of said intercepts an identity of a pair of polar sections nearest said intercept in a grid of polar sections superimposed on said character image and centered at said centroid, wherein said input data string further comprises said identity of said pair of polar sections.
Claim 6
Dependent Claim
36 words
The system of claim 1 wherein said radial intercept means comprises means for generating a histogram of the intercept count at each one of said plurality of radii, wherein said input data string comprises said histogram.
Claim 7
Dependent Claim
18 words
The system of claim 1 wherein said transition points comprise end points and branch points in said image.
Claim 8
Dependent Claim
44 words
The system of claim 1 further comprising curve feature extraction means for making an identification of which predetermined regions of said character image match one of a set of arc templates, wherein said input data string further comprises said identification of said predetermined regions.
Claim 9
Dependent Claim
27 words
The system of claim 7 wherein said curve feature extraction means comprises means for making said identification for each one of a set of four quarter-arc templates.
Claim 10
Dependent Claim
15 words
The system of claim 8 wherein said predetermined regions comprise quadrants of said character image.
Claim 11
Dependent Claim
46 words
The system of claim 1 further comprising line feature extraction means for making an identification of at least one of a plurality of selected lines having predetermined orientations correlated with said character image, wherein said input data string further comprises said identification of said selected line.
Claim 12
Dependent Claim
39 words
The system of claim 10 wherein said plurality of selected lines comprise vertical, horizontal, minor diagonal and major diagonal lines, whereby said line feature extraction means comprises means for making said identification for each one of said selected lines.
Claim 13
Dependent Claim
47 words
The system of claim 10 wherein said line feature extraction means comprises means for determining whether the number of "ON" pixels in each one of a plurality of parallel linear regions of said character image characterized by one of said predetermined orientations exceeds a predetermined threshold number.
Claim 14
Dependent Claim
113 words
A feature-based optical character recognition method for extracting features from an individual character image segmented from a document image, comprising: counting a number of intercepts between at least one of a plurality of circles of predetermined radii in said character image and boundary transitions in said character image; determining for each transition point in said image an identity of a pair of regions in a grid superimposed on said character image nearest the transition point, whereby said number of intercepts and said identity of said pair of regions comprise an input data string; and comparing said input data string with a set of reference data strings corresponding to a set of known symbols.
Claim 15
Dependent Claim
113 words
A feature-based optical character recognition method for extracting features from an individual character image segmented from a document image, comprising: counting a number of intercepts between at least one of a plurality of circles of predetermined radii in said character image and boundary transitions in said character image; determining for each transition point in said image an identity of a pair of regions in a grid superimposed on said character image nearest the transition point, whereby said number of intercepts and said identity of said pair of regions comprise an input data string; and comparing said input data string with a set of reference data strings corresponding to a set of known symbols.
Claim 16
Dependent Claim
37 words
The method of claim 13 wherein said counting step comprises: locating a centroid and boundary of an object in said character image; centering said one circle at said centroid; and selecting the radius of said one circle.
Claim 17
Dependent Claim
51 words
The method of claim 14 wherein said selecting step comprises: locating with respect to said centroid a reference radius between a minimum radial peak and a maximum radial valley in said boundary; and computing said radius as a weighted average of said reference radius an a mean radius of said boundary.
Claim 18
Dependent Claim
60 words
The method of claim 14 wherein said counting step further comprises: determining for each one of said intercepts an identity of a pair of polar sections nearest said intercept in a grid of polar sections superimposed on said character image and centered at said centroid, wherein said input data string further comprises said identity of said pair of polar sections.
Claim 19
Dependent Claim
33 words
The method of claim 13 wherein said counting step comprises generating a histogram of the intercept count at each one of said plurality of radii, wherein said input data string comprises said histogram.
Claim 20
Dependent Claim
18 words
The method of claim 13 wherein said transition points comprise end points and branch points in said image.
Claim 21
Dependent Claim
39 words
The method of claim 13 further comprising making an identification of which predetermined regions of said character image match one of a set of arc templates, wherein said input data string further comprises said identification of said predetermined regions.
Claim 22
Dependent Claim
30 words
The method of claim 19 wherein said step of making said identification of said predetermined regions comprises making said identification for each one of a set of four quarter-arc templates.
Claim 23
Dependent Claim
15 words
The method of claim 20 wherein said predetermined regions comprise quadrants of said character image.
Claim 24
Dependent Claim
41 words
The method of claim 13 further comprising making an identification of at least one of a plurality of selected lines having predetermined orientations correlated with said character image, wherein said input data string further comprises said identification of said selected line.
Claim 25
Dependent Claim
20 words
The method of claim 22 wherein said plurality of selected lines comprise vertical, horizontal, minor diagonal and major diagonal lines.
Claim 26
Dependent Claim
50 words
The method of claim 22 wherein said step of making said identification of said selected line comprises determining whether the number of "ON" pixels in each one of a plurality of parallel linear regions of said character image characterized by one of said predetermined orientations exceeds a predetermined threshold number.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-30 | 1995-04-01 | 1995-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-30 | 1999-04-01 | 1999-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-30 | 2003-04-01 | 2003-10-01 | $7700.00 | Window Closed / Lapsed |