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US5533144A
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Anti-counterfeit pattern detector and method
Assignee: Xerox Corp
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Filing: 1994-10-17
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Granted: 1996-07-02
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Expires: 2014-10-17
Abstract
Abstract An anti-counterfeit detector and method for identifying whether a platen image portion to be photocopied contains one or several pre-selected monetary note patterns. The detection is performed in a rotation and shift invariant manner. Specifically, the pattern can be of any orientation and at any location of the image. Moreover, it can be embedded in any complicated image background.
Inventors
- 👤 Zhigang Fan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:44
CPC Classifications
G; G07; G07D; G07D7/00; G07D7/06; G07D7/12; G06; G06V; G06V10/00; G06V10/20; G06V10/24; G06V10/245
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
181 words
An anti-counterfeit detector for detecting whether an image to be photocopied is a currency note, the detector comprising: storage means for storing a plurality of templates, each of said plurality of templates comprising at least one predetermined anchor point; examining means for examining a portion of said image to be photocopied and for determining whether said portion contains a predetermined pixel intensity arrangement, wherein said predetermined pixel intensity arrangement is an edge and said examining means comprises means for calculating edge strength within said portion in accordance with the following equations: f(x,y)=|d.sub.V |.sup.3 (x,y)+|d.sub.H |.sup.3 (x,y) and W=Σf(x,y) where d V and d H are differences in intensity of neighboring pixels in vertical and horizontal directions respectively, W is edge strength and summation is over said portion; orientation determining means for determining an orientation of said predetermined pixel intensity arrangement; positioning means for positioning said plurality of templates in alignment with said predetermined pixel intensity arrangement in accordance with said orientation determined by said orientation determining means; matching means for comparing said plurality of templates to said predetermined pixel intensity arrangement.
Claim 2
Dependent Claim
181 words
An anti-counterfeit detector for detecting whether an image to be photocopied is a currency note, the detector comprising: storage means for storing a plurality of templates, each of said plurality of templates comprising at least one predetermined anchor point; examining means for examining a portion of said image to be photocopied and for determining whether said portion contains a predetermined pixel intensity arrangement, wherein said predetermined pixel intensity arrangement is an edge and said examining means comprises means for calculating edge strength within said portion in accordance with the following equations: f(x,y)=|d.sub.V |.sup.3 (x,y)+|d.sub.H |.sup.3 (x,y) and W=Σf(x,y) where d V and d H are differences in intensity of neighboring pixels in vertical and horizontal directions respectively, W is edge strength and summation is over said portion; orientation determining means for determining an orientation of said predetermined pixel intensity arrangement; positioning means for positioning said plurality of templates in alignment with said predetermined pixel intensity arrangement in accordance with said orientation determined by said orientation determining means; matching means for comparing said plurality of templates to said predetermined pixel intensity arrangement.
Claim 3
Dependent Claim
22 words
An anti-counterfeit detector according to claim 1, wherein if said edge strength does not exceed a predetermined threshold, said portion is discarded.
Claim 4
Dependent Claim
78 words
An anti-counterfeit detector according to claim 1, wherein said orientation determining means comprises means for determining edge orientation φ in accordance with the following equations: x.sub.0 ={Σf(x,y)x}/W and y.sub.0 ={Σf(x,y)y}/W wherein x and y are the coordinates of each of said pixel intensity arrangement, f(x,y)=|d V | 3 (x,y)+|d H | 3 (x,y), where d V and d H are differences in intensity of neighboring pixels of said pixel intensity arrangement, W=Σf(x,y) over said pixel intensity arrangement, and
Claim 5
Dependent Claim
63 words
φ=θ+0. 5π, if ε≧0.5 and φ=θ if ε<0.5 where θ=0.5 tan.sup.-1 (2M.sub.xy /M.sub.x M.sub.y) ε=(M.sub.x sin.sup.2 θ+M.sub.y cos.sup.2 θ+2M.sub.xy sin θ cos θ)/(M.sub.x +M.sub.y) where M x , M y and M xy refer to second order moments defined as M.sub.x =Σf(x,y)(x-x.sub.0).sup.2 M.sub.y =Σf(x,y)(y-y.sub.0).sup.2 and M.sub.xy =Σf(x,y)(x-x.sub.0)(y-y.sub.0).sup.2 and summation is over a circular area preselected diameter center at (x 0 ,y 0 ).
Claim 6
Dependent Claim
63 words
φ=θ+0. 5π, if ε≧0.5 and φ=θ if ε<0.5 where θ=0.5 tan.sup.-1 (2M.sub.xy /M.sub.x M.sub.y) ε=(M.sub.x sin.sup.2 θ+M.sub.y cos.sup.2 θ+2M.sub.xy sin θ cos θ)/(M.sub.x +M.sub.y) where M x , M y and M xy refer to second order moments defined as M.sub.x =Σf(x,y)(x-x.sub.0).sup.2 M.sub.y =Σf(x,y)(y-y.sub.0).sup.2 and M.sub.xy =Σf(x,y)(x-x.sub.0)(y-y.sub.0).sup.2 and summation is over a circular area preselected diameter center at (x 0 ,y 0 ).
Claim 7
Dependent Claim
14 words
An anti-counterfeit detector according to claim 3, wherein said preselected diameter is 8 pixels.
Claim 8
Dependent Claim
47 words
An anti-counterfeit detector according to claim 4, wherein said positioning means comprises means for rotating said template according to the following equation: x'=x cos φ+y sin φ and y'=-x sin φ+y cos φ where (x,y) and (x',y') are coordinates of a pixel before and after rotation respectively.
Claim 9
Dependent Claim
53 words
An anti-counterfeit detector according to claim 1, wherein said matching means further comprises means for determining matching strength r in accordance with the following equation: ##EQU2## where v(x,y) and t(x,y) are intensity values at (x,y) in the image and each of the plurality of templates, respectively, and summation is over a template size.
Claim 10
Dependent Claim
20 words
An anti-counterfeit detector according to claim 6, wherein a match is indicated by r being greater than a preset threshold.
Claim 11
Dependent Claim
164 words
An anti-counterfeit method for detecting whether an image to be photocopied is a currency note, the method comprising the steps of: storing a plurality of templates, each of said plurality of templates comprising at least one predetermined anchor point; examining a portion of said image to be photocopied and determining whether said portion contains a predetermined pixel intensity arrangement, wherein said predetermined pixel intensity arrangement comprises an edge and the step of examining comprises determining edge strength within said portion accordance with the following equations: f(x,y)=|d.sub.V |.sup.3 (x,y)+|d.sub.H |.sup.3 (x,y) and W=Σf(x,y) where d V and d H are differences in intensity of neighboring pixels in vertical and horizontal directions respectively, W is edge strength and summation is over said portion; determining an orientation of said predetermined pixel intensity arrangement; positioning said templates in alignment with said predetermined pixel intensity arrangement in accordance with said orientation determined by said orientation determination means; and comparing said plurality of templates to said predetermined pixel intensity arrangement.
Claim 12
Dependent Claim
164 words
An anti-counterfeit method for detecting whether an image to be photocopied is a currency note, the method comprising the steps of: storing a plurality of templates, each of said plurality of templates comprising at least one predetermined anchor point; examining a portion of said image to be photocopied and determining whether said portion contains a predetermined pixel intensity arrangement, wherein said predetermined pixel intensity arrangement comprises an edge and the step of examining comprises determining edge strength within said portion accordance with the following equations: f(x,y)=|d.sub.V |.sup.3 (x,y)+|d.sub.H |.sup.3 (x,y) and W=Σf(x,y) where d V and d H are differences in intensity of neighboring pixels in vertical and horizontal directions respectively, W is edge strength and summation is over said portion; determining an orientation of said predetermined pixel intensity arrangement; positioning said templates in alignment with said predetermined pixel intensity arrangement in accordance with said orientation determined by said orientation determination means; and comparing said plurality of templates to said predetermined pixel intensity arrangement.
Claim 13
Dependent Claim
22 words
The method according to claim 8, wherein an examined portion is discarded if its edge strength does not exceed a preselected threshold.
Claim 14
Dependent Claim
137 words
The method according to claim 8, wherein the step of determining comprises determining edge orientation φ in accordance with the following equations: x.sub.0 ={Σf(x,y)x}/W and y.sub.0 ={Σf(x,y)y}/W wherein x and y are the coordinates of each of said pixel intensity arrangement, f(x,y)=|d V | 3 (x,y)+|d H | 3 (x,y), where d V and d H are differences in intensity of neighboring pixels of said pixel intensity arrangement, W=Σf(x,y) over said pixel intensity arrangement, and φ=θ+0.5π, if ε≧0.5 and φ=θ if ε<0.5 where θ=0.5 tan.sup.-1 (2M.sub.xy /M.sub.x M.sub.y) ε=(M.sub.x sin.sup.2 θ+M.sub.y cos.sup.2 θ+2M.sub.xy sin θ cos θ)/(M.sub.x +M.sub.y) where M x , M y and M xy refer to second order moments defined as M.sub.x =Σf(x,y)(x-x.sub.0).sup.2 M.sub.y =Σf(x,y)(y-y.sub.0).sup.2 and M.sub.xy =Σf(x,y)(x-x.sub.0)(y-y.sub.0).sup.2 and summation is over a circular area preselected diameter center at (x 0 ,y 0 ).
Claim 15
Dependent Claim
13 words
The method according to claim 10, wherein said preselected diameter is 8 pixels.
Claim 16
Dependent Claim
46 words
The method according to claim 10, wherein the step of aligning comprises rotation of said templates according to the following equations: x'=x cos φ+y sin φ and y'=-x sin φ+y cos φ where (x,y) and (x',y') are coordinates of a pixel before and after rotation respectively.
Claim 17
Dependent Claim
47 words
The method according to claim 8, wherein the step of comparing comprises determining matching strength r in accordance with the following equation: ##EQU3## where v(x,y) and t(x,y) are intensity values at (x,y) in a smoothed platen image and template image respectively, and summation is over template size.
Claim 18
Dependent Claim
20 words
An anti-counterfeit detector according to claim 13, wherein a match is indicated by r being greater than a preset threshold.
References Cited (Backward Citations)
US4153897A
Cited
US5216724A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-07-02 | 2000-01-01 | 2000-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-02 | 2004-01-01 | 2004-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-02 | 2008-01-01 | 2008-07-02 | $7700.00 | Window Closed / Lapsed |