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US6043900A
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Method and system for automatically detecting a background type of a scanned document utilizing a leadedge histogram thereof
Assignee: Xerox Corp
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Filing: 1998-03-31
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Granted: 2000-03-28
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Expires: 2018-03-31
Abstract
Abstract A method and system automatically determines proper background values for a document. A histogram of the document is generated and it is determined whether a background characteristic of the document is uniform. If the background is uniform, a white background value is set equal to a first calculated white peak value. If the background is non-uniform, the white background value is set equal to a second calculated white peak value. A foreground value of the document is analyzed for validity when it is determined that a background characteristic of the document is uniform. A black background value is set equal to a black peak value calculated from the histogram when it is determined that a foreground value of the document is valid.
Inventors
- 👤 Xiao-fan Feng
- 👤 Roger L. Triplett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:52
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/4072; G; G06; G06T; G06T5/00; G06T5/40; G06T5/90; G06T5/92; G06T2207/00; G06T2207/10; G06T2207/10004; G06T2207/10008
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
145 words
A method for automatically determining proper background values for a document, comprising the steps of: (a) generating a histogram of the document; (b) determining if a background characteristic of the document is uniform; (c) setting a white background value equal to a first calculated white peak value when said step (b) determines that a background characteristic of the document is uniform; (d) setting a white background value equal to a second calculated white peak value when said step (b) determines that a background characteristic of the document is non-uniform; (e) determining if a foreground value of the document is valid when said step (b) determines that a background characteristic of the document is uniform; and (f) setting a black background value equal to a black peak value calculated from the histogram when said step (e) determines that a foreground value of the document is valid.
Claim 2
Independent Claim
145 words
A method for automatically determining proper background values for a document, comprising the steps of: (a) generating a histogram of the document; (b) determining if a background characteristic of the document is uniform; (c) setting a white background value equal to a first calculated white peak value when said step (b) determines that a background characteristic of the document is uniform; (d) setting a white background value equal to a second calculated white peak value when said step (b) determines that a background characteristic of the document is non-uniform; (e) determining if a foreground value of the document is valid when said step (b) determines that a background characteristic of the document is uniform; and (f) setting a black background value equal to a black peak value calculated from the histogram when said step (e) determines that a foreground value of the document is valid.
Claim 3
Dependent Claim
67 words
The method as claimed in claim 1, wherein said step (b) comprises the substeps of: (b1) calculating a white peak ratio value which is proportional to a ratio of the calculated white peak value and a calculated half white peak power width value; and (b2) determining that a background characteristic of the document is uniform when the white peak ratio value is larger than a predetermined value.
Claim 4
Dependent Claim
53 words
The method as claimed in claim 1, wherein the first calculated white peak value is equal to P 0 -C(P 0 -P 1/4 ) where P 0 is a white peak value calculated from the histogram, P 1/4 is a quarter white peak value calculated from the histogram, and C is a constant.
Claim 5
Dependent Claim
18 words
The method as claimed in claim 3, wherein C equals 2.375 when P 0 is greater than 150.
Claim 6
Dependent Claim
23 words
The method as claimed in claim 3, wherein C equals 2.375(P 0 /150) 2 when P 0 is less than or equal 150.
Claim 7
Dependent Claim
34 words
The method as claimed in claim 3, wherein C equals 2.375 when P 0 is greater than 150 and C equals 2.375(P 0 /150) 2 when P 0 is less than or equal 150.
Claim 8
Dependent Claim
56 words
The method as claimed in claim 6, wherein said step (e) comprises the substeps of: (e1) calculating a foreground value threshold equal to the first calculated white peak value divided by a predetermined value; and (b2) determining that a foreground value is valid when a calculated black peak value is less than the foreground value threshold.
Claim 9
Dependent Claim
13 words
The method as claimed in claim 7, wherein the predetermined value is 2.5.
Claim 10
Dependent Claim
47 words
The method as claimed in claim 1, further comprising the steps of: (g) setting a black background value equal to a white peak value calculated from the histogram divided by a predetermined value when said step (e) determines that a foreground value of the document is invalid.
Claim 11
Independent Claim
166 words
A system for automatically determining proper background values for a document, comprising: a histogram circuit to generate a histogram of the document; and a background value generation and detection circuit to determine if a background characteristic of the document is uniform; said background value generation and detection circuit setting a white background value equal to a first calculated white peak value when it is determined that a background characteristic of the document is uniform and setting a white background value equal to a second calculated white peak value when it is determined that a background characteristic of the document is non-uniform; said background value generation and detection circuit determining if a foreground value of the document is valid when it is determined that a background characteristic of the document is uniform; said background value generation and detection circuit setting a black background value equal to a black peak value calculated from the histogram when it is determined that a foreground value of the document is valid.
Claim 12
Independent Claim
166 words
A system for automatically determining proper background values for a document, comprising: a histogram circuit to generate a histogram of the document; and a background value generation and detection circuit to determine if a background characteristic of the document is uniform; said background value generation and detection circuit setting a white background value equal to a first calculated white peak value when it is determined that a background characteristic of the document is uniform and setting a white background value equal to a second calculated white peak value when it is determined that a background characteristic of the document is non-uniform; said background value generation and detection circuit determining if a foreground value of the document is valid when it is determined that a background characteristic of the document is uniform; said background value generation and detection circuit setting a black background value equal to a black peak value calculated from the histogram when it is determined that a foreground value of the document is valid.
Claim 13
Dependent Claim
65 words
The system as claimed in claim 10, wherein said background value generation and detection circuit calculates a white peak ratio value which is proportional to a ratio of the calculated white peak value and a calculated half white peak power width value and determines that a background characteristic of the document is uniform when the white peak ratio value is larger than a predetermined value.
Claim 14
Dependent Claim
53 words
The system as claimed in claim 10, wherein the first calculated white peak value is equal to P 0 -C(P 0 -P 1/4 ) where P 0 is a white peak value calculated from the histogram, P 1/4 is a quarter white peak value calculated from the histogram, and C is a constant.
Claim 15
Dependent Claim
18 words
The system as claimed in claim 12, wherein C equals 2.375 when P 0 is greater than 150.
Claim 16
Dependent Claim
23 words
The system as claimed in claim 12, wherein C equals 2.375(P 0 /150) 2 when P 0 is less than or equal 150.
Claim 17
Dependent Claim
34 words
The system as claimed in claim 12, wherein C equals 2.375 when P 0 is greater than 150 and C equals 2.375(P 0 /150) 2 when P 0 is less than or equal 150.
Claim 18
Dependent Claim
54 words
The system as claimed in claim 15, wherein said background value generation and detection circuit calculates a foreground value threshold equal to the first calculated white peak value divided by a predetermined value and determines that a foreground value is valid when a calculated black peak value is less than the foreground value threshold.
Claim 19
Dependent Claim
13 words
The system as claimed in claim 16, wherein the predetermined value is 2.5.
Claim 20
Dependent Claim
48 words
The method as claimed in claim 10, wherein said background value generation and detection circuit sets a black background value equal to a white peak value calculated from the histogram divided by a predetermined value when it is determined that a foreground value of the document is invalid.
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) | 2003-03-28 | 2003-09-27 | 2004-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-03-28 | 2007-09-27 | 2008-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-03-28 | 2011-09-27 | 2012-03-28 | $7700.00 | Window Closed / Lapsed |