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US5159645A
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Method for recognizing concavities in an image subject to character recognition
Assignee: Sharp Corp
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Filing: 1991-10-29
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Granted: 1992-10-27
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Expires: 2011-10-29
Abstract
Abstract An image processing method for finding concavity of a configuration comprising steps; arranging boundary pixels of the configuration according to chain order with indicating top points on convex hull of the configuration; and determining that a concavity is defined by the boundary pixels when a boundary pixel of a chain code is found, which chain code indicates a concavity.
Inventors
- 👤 Ryohei Kumagai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:09
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/40; G06V10/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
148 words
An image processing method for recognizing a configuration in an image from a characteristics representation of the configuration comprising the steps of: representing the image as digital pixels; generating a convex hull for the configuration, said convex hull delineated by a series of pixels connecting top points of the configuration; generating a representation of the configuration as characteristics of the difference between the convex hull and the configuration, said characteristics including concavities in the configuration; and wherein the step of generating a representation of the configuration includes steps of: representing a contour of the configuration between two adjacent top points as a series of chain codes, said top points defining a straight line segment; calculating separation distances between the contour of the configuration and the straight line segment; and generating a representation of the contour as a concavity when a separation distance is greater than a predetermined value.
Claim 2
Dependent Claim
148 words
An image processing method for recognizing a configuration in an image from a characteristics representation of the configuration comprising the steps of: representing the image as digital pixels; generating a convex hull for the configuration, said convex hull delineated by a series of pixels connecting top points of the configuration; generating a representation of the configuration as characteristics of the difference between the convex hull and the configuration, said characteristics including concavities in the configuration; and wherein the step of generating a representation of the configuration includes steps of: representing a contour of the configuration between two adjacent top points as a series of chain codes, said top points defining a straight line segment; calculating separation distances between the contour of the configuration and the straight line segment; and generating a representation of the contour as a concavity when a separation distance is greater than a predetermined value.
Claim 3
Dependent Claim
30 words
An image processing method according to claim 1, wherein boundary pixels of said configuration are divided into groups of possible chain codes included in a area other than a concavity.
Claim 4
Dependent Claim
14 words
An image processing method according to claim 2, wherein said groups comprise four quadrants.
Claim 5
Dependent Claim
25 words
An image processing method according to claim 3, wherein said quadrants are defined by most upper, most leftward, most lower and most rightward boundary pixels.
Claim 6
Dependent Claim
69 words
An image processing method according to claim 4, wherein said possible chain codes are defined as follows; between most upper and most leftward boundary pixels: chain code=1, 5 or 6 between most left and most lower boundary pixels: chain code=6, 7 or 0 between most lower and most rightward boundary pixels: chain code=0, 1 or 2 between most rightward and most upper boundary pixels: chain code=2, 3 or 4.
Claim 7
Dependent Claim
42 words
An image processing method according to claim 2, wherein the step of calculating separation distances includes steps of: calculating distance increments for each chain code; and integrating distance increments of pixels as processed from one of said top points toward the other.
Claim 8
Dependent Claim
56 words
An image processing method according to claim 2, wherein number of boundary pixels are counted between said two top points on evaluating chain codes or on calculating distances, and total number of boundary pixels are counted when said boundary pixels are found to define a concavity, so as to calculate inner peripheral length of a concavity.
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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) | 1995-10-27 | 1996-04-27 | 1996-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-10-27 | 2000-04-27 | 2000-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-10-27 | 2004-04-27 | 2004-10-27 | $7700.00 | Window Closed / Lapsed |