Patent US5633947A successfully refreshed from Google Patents.
US5633947A
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Method and apparatus for fingerprint characterization and recognition using auto correlation pattern
Assignee: EMI Group Ltd
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Filing: 1994-10-12
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Granted: 1997-05-27
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Expires: 2014-10-12
Abstract
Abstract Apparatus for use with an autocorrelation technique for characterizing fingerprints includes an imaging device for providing an image of a fingerprint. The image so produced is then utilized by a microprocessor in order to generate an autocorrelation pattern for statistical comparison with stored data so as to determine whether the image of the fingerprint under test is derived from the fingerprint representated by the stored data.
Inventors
- 👤 Alastair Sibbald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 07:45
CPC Classifications
G; G06; G06V; G06V40/00; G06V40/10; G06V40/12; G06V40/1365
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
218 words
An apparatus for characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint, the apparatus comprising: a fingerprint image capturing means for generating an image of the fingerprint under test comprising a receiving surface adapted to receive a surface of a finger bearing the fingerprint under test and an illumination device for illuminating said surface; transducer means optically connected to said capturing means for receiving said image and for generating electrical signals representative of said image in response thereto; storage means, connected to said transducer means, for storing said electrical signals as a binary image of the fingerprint; replicating means for producing a replica of the binary image; combining means for effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps; sampling means for sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument; and storing means for storing the sets of data.
Claim 2
Independent Claim
218 words
An apparatus for characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint, the apparatus comprising: a fingerprint image capturing means for generating an image of the fingerprint under test comprising a receiving surface adapted to receive a surface of a finger bearing the fingerprint under test and an illumination device for illuminating said surface; transducer means optically connected to said capturing means for receiving said image and for generating electrical signals representative of said image in response thereto; storage means, connected to said transducer means, for storing said electrical signals as a binary image of the fingerprint; replicating means for producing a replica of the binary image; combining means for effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps; sampling means for sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument; and storing means for storing the sets of data.
Claim 3
Dependent Claim
11 words
An apparatus according to claim 1 wherein the sectors are quadrants.
Claim 4
Dependent Claim
13 words
An apparatus according to claim 1 wherein the incremental steps equal 30 degrees.
Claim 5
Dependent Claim
55 words
An apparatus according to claim 1 and further comprising retrieval means for retrieving sets of data obtained from one further fingerprint for comparison with the sets of data obtained from the said fingerprint to determine, without revealing any information regarding the actual fingerprints, if the compared sets of data were obtained from the same fingerprint.
Claim 6
Dependent Claim
20 words
An apparatus according to claim 1 wherein said previously characterized fingerprint is one of a plurality of previously characterized fingerprints.
Claim 7
Dependent Claim
19 words
An apparatus according to claim 1 and further comprising masking means for masking an edge of said autocorrelation pattern.
Claim 8
Dependent Claim
20 words
An apparatus according to claim 1 wherein said displacement modulus is constant and said incremental steps are periodic and regular.
Claim 9
Dependent Claim
18 words
An apparatus according to claim 1 wherein said fractional part is about 1/2 the mean fingerprint inter-ridge spacing.
Claim 10
Independent Claim
170 words
A method of characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint comprising the steps of: generating an image of the fingerprint under test by receiving a surface of a finger bearing the fingerprint under test and illuminating said surface; generating electrical signals representative of said image in response thereto; storing said electrical signals as a binary image of the fingerprint; producing a replica of the binary image; effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps; sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument; and storing the sets of data.
Claim 11
Independent Claim
170 words
A method of characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint comprising the steps of: generating an image of the fingerprint under test by receiving a surface of a finger bearing the fingerprint under test and illuminating said surface; generating electrical signals representative of said image in response thereto; storing said electrical signals as a binary image of the fingerprint; producing a replica of the binary image; effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps; sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument; and storing the sets of data.
Claim 12
Dependent Claim
11 words
A method according to claim 9 wherein the sectors are quadrants.
Claim 13
Dependent Claim
13 words
A method according to claim 9 wherein the incremental steps equal 30 degrees.
Claim 14
Dependent Claim
61 words
A method according to claim 9 and further comprising the steps of retrieving sets of data obtained from one further fingerprint and comparing the sets of data retrieved with the sets of data obtained from the fingerprint under test to determine, without revealing any information regarding the actual fingerprints, if the compared sets of data were obtained from the same fingerprint.
Claim 15
Dependent Claim
19 words
A method according to claim 9 and further comprising the step of masking an edge of said autocorrelation pattern.
Claim 16
Dependent Claim
20 words
A method according to claim 9 wherein said displacement modulus is constant and said incremental steps are periodic and regular.
Claim 17
Dependent Claim
20 words
A method according to claim 9 wherein said previously characterized fingerprint is one of a plurality of previously characterized fingerprints.
Claim 18
Dependent Claim
14 words
A method according to claim 12 wherein the step of comparing is performed optically.
Claim 19
Dependent Claim
14 words
A method according to claim 12 wherein the step of comparing is performed electrically.
Claim 20
Dependent Claim
18 words
A method according to claim 9 wherein said fractional part is about 1/2 the mean fingerprint inter-ridge spacing.
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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) | 2000-05-26 | 2000-11-25 | 2001-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-05-26 | 2004-11-25 | 2005-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-05-26 | 2008-11-25 | 2009-05-27 | $7700.00 | Window Closed / Lapsed |