US5212739A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noise tolerant optical character recognition system
Assignee: HP Inc
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Filing: 1992-04-24
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Granted: 1993-05-18
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Expires: 2012-04-24
Abstract
Abstract Disclosed is a method of optical character recognition that first segments a graphical page image into word images. The method obtains a set of features by extracting smaller outlines of the dark regions in the word images, and then further dissecting each of the smaller outlines into small sections called micro-features. Micro-features are simply sections of character outlines, therefore, they can easily be extracted from the outlines of an entire word without any knowledge about character segmentation boundaries. Micro-features are extracted from an outline by finding the local extremities of the outline and then defining a micro-feature between each pair of sequential extremities. Once extracted, the micro-features are compared to micro-features from an ideal character in order to classify a character, and convert it into a character code.
Inventors
- 👤 Dan S. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 00:52
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/10; G06V30/18; G06V30/182
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
199 words
A system for optical character recognition comprising: means for converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; means for separating said graphical image into a plurality of word images; means for scanning said word images and for producing a plurality of micro-features for each of said word images comprising means for separating said word images into a plurality of outlines each defined by a boundary between pixels of different intensity within said word images, means for locating all extremities of each of said outlines, comprising means for combining each pair of adjacent edge points of said outlines into a plurality of segments, means for computing a directional orientation for each of said segments, means for combining adjacent segments having the same directional orientation into a plurality of sections, and means for defining zero or more points in each of said sections as an extremity, and means for producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and means for converting said micro-features into a set of coded characters equivalent to said word.
Claim 2
Independent Claim
199 words
A system for optical character recognition comprising: means for converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; means for separating said graphical image into a plurality of word images; means for scanning said word images and for producing a plurality of micro-features for each of said word images comprising means for separating said word images into a plurality of outlines each defined by a boundary between pixels of different intensity within said word images, means for locating all extremities of each of said outlines, comprising means for combining each pair of adjacent edge points of said outlines into a plurality of segments, means for computing a directional orientation for each of said segments, means for combining adjacent segments having the same directional orientation into a plurality of sections, and means for defining zero or more points in each of said sections as an extremity, and means for producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and means for converting said micro-features into a set of coded characters equivalent to said word.
Claim 3
Dependent Claim
47 words
The system of claim 1 wherein said means for defining zero or more points in a segment as extremities comprises: means for defining a midpoint of all horizontal and vertical sections as an extremity; and means for defining an end point of selected sections as an extremity.
Claim 4
Dependent Claim
24 words
The system of claim 1 wherein said means for producing a micro-feature further comprises means for scaling said micro-feature to produce a normalized micro-feature.
Claim 5
Dependent Claim
60 words
The system of claim 1 wherein said micro-feature comprises: a length measured as a straight distance between said extremities; a center point located at a center of said line between said extremities; an angle measured from a horizontal direction to said line between said extremities; zero or more bulge lengths, measured from said line between said extremities to said outline.
Claim 6
Dependent Claim
27 words
The system of claim 4 wherein said zero or more bulge lengths comprises two bulge lengths measured at points one-third and two-thirds the distance between said extremities.
Claim 7
Independent Claim
217 words
A system for optical character recognition comprising: means for converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; means for separating said graphical image into a plurality of group images, each said group image having one or more character images; means for scanning said group images and for producing a plurality of micro-features for each of said group images comprising means for operating said group image into a plurality of outlines each defined by a boundary between pixels of different intensity within said group image, means for locating all extremities of each of said outlines, comprising means for combining each pair of adjacent edge points of said outlines into a plurality of segments, means for computing a directional orientation for each of said segments, means for combining adjacent segments having the same directional orientation into a plurality of sections, and means for defining zero or more points in each of said sections as an extremity, and means for producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and means for converting said micro-features into a set of coded characters each equivalent to one of said character images in said group image.
Claim 8
Independent Claim
217 words
A system for optical character recognition comprising: means for converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; means for separating said graphical image into a plurality of group images, each said group image having one or more character images; means for scanning said group images and for producing a plurality of micro-features for each of said group images comprising means for operating said group image into a plurality of outlines each defined by a boundary between pixels of different intensity within said group image, means for locating all extremities of each of said outlines, comprising means for combining each pair of adjacent edge points of said outlines into a plurality of segments, means for computing a directional orientation for each of said segments, means for combining adjacent segments having the same directional orientation into a plurality of sections, and means for defining zero or more points in each of said sections as an extremity, and means for producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and means for converting said micro-features into a set of coded characters each equivalent to one of said character images in said group image.
Claim 9
Dependent Claim
47 words
The system of claim 6 wherein said means for defining zero or more points in a segment as extremities comprises: means for defining a midpoint of all horizontal and vertical sections as an extremity; and means for defining an end point of selected sections as an extremity.
Claim 10
Dependent Claim
24 words
The system of claim 6 wherein said means for producing a micro-feature further comprises means for scaling said micro-feature to produce a normalized micro-feature.
Claim 11
Dependent Claim
60 words
The system of claim 6 wherein said micro-feature comprises: a length measured as a straight distance between said extremities; a center point located at a center of said line between said extremities; an angle measured from a horizontal direction to said line between said extremities; zero or more bulge lengths, measured from said line between said extremities to said outline.
Claim 12
Dependent Claim
27 words
The system of claim 9 wherein said zero or more bulge lengths comprises two bulge lengths measured at points one-third and two-thirds the distance between said extremities.
Claim 13
Independent Claim
197 words
A method for optical character recognition comprising the steps of: (a) converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; (b) separating said graphical image into a plurality of group images; (c) scanning said group images to produce a plurality of micro-features for each of said group images comprising the steps of (c1) separating said group image into a plurality of outlines each defined by a boundary between edge points within said group image, (c2) locating all extremities of each of said outlines, comprising the steps of (c2A) combining each pair of adjacent pixels of said outlines into a plurality of segments; (c2B) computing a directional orientation for each of said segments; (c2C) combining adjacent segments having the same directional orientation into a plurality of sections; and (c2D) defining zero or more points in each of said sections as an extremity, and (c3) producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and (d) converting said micro-features into a set of coded characters each equivalent to a character within said group.
Claim 14
Independent Claim
197 words
A method for optical character recognition comprising the steps of: (a) converting a page having plurality of text printed thereon into a graphical image containing a plurality of pixel elements representative of said text; (b) separating said graphical image into a plurality of group images; (c) scanning said group images to produce a plurality of micro-features for each of said group images comprising the steps of (c1) separating said group image into a plurality of outlines each defined by a boundary between edge points within said group image, (c2) locating all extremities of each of said outlines, comprising the steps of (c2A) combining each pair of adjacent pixels of said outlines into a plurality of segments; (c2B) computing a directional orientation for each of said segments; (c2C) combining adjacent segments having the same directional orientation into a plurality of sections; and (c2D) defining zero or more points in each of said sections as an extremity, and (c3) producing a single micro-feature between each pair of said extremities, said micro-feature being terminated at each of said pair of extremities; and (d) converting said micro-features into a set of coded characters each equivalent to a character within said group.
Claim 15
Dependent Claim
38 words
The method of claim 11 wherein step (c2D) further comprises the steps of: (c2D1) defining a midpoint of all horizontal and vertical sections as an extremity; and (c2D2) defining an end point of selected sections as an extremity.
Claim 16
Dependent Claim
18 words
The method of claim 11 further comprising the step of scaling said micro-feature to produce a normalized micro-feature.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-17 | 1996-11-16 | 1997-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-17 | 2000-11-16 | 2001-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-17 | 2004-11-16 | 2005-05-18 | $7700.00 | Window Closed / Lapsed |