EP0253935B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Weighted-pixel characteristic sensing
Assignee: Light Signatures Inc
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Filing: 1986-10-16
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Granted: 1993-02-03
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Expires: 2006-10-16
Abstract
Abstract A method and system for sensing a characteristic (e.g. translucency) of a document (10) utilises radiation (17) from a specific window area (16) of the document (10). The radiation (17) is sensed by a sensor (18) with pixel dissection (P1 - P3), that affords pixels (P2) of a central location of the window area (16), a greater (x2) weighting so as to attribute enhanced significance to the central portion of the window area (16), whereby tolerance to misalignment with respect to the window area (16) is increased. Data signals in accordance with the weighted pixel signals are compared (62 Fig 3; 120 Fig 6) with stored values (64 Fig 3; 122 Fig 6) for the purpose of document authentication (66 Fig 3; 124 Fig 6). Pixel-weighting techniques used include filtering incident and transmitted light (46, 54 Fig 3, Fig 4), algebraically weighting derived signals (Figs 5, 6), and overlapping the sensed pixels (Fig 7).
Inventors
- 👤 David G. Gold
- 👤 Vahakn K. Gharibian
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 08:52
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/409; H04N1/4092; G; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10; G06K19/14; G06K7/00; G06K7/10; G06K7/14; G06V; G06V30/00; G06V30/10; G06V30/14; G06V30/1437; G07; G07D; G07D7/00; G07D7/20; H04N1/024; H04N1/028; H04N1/029
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
106 words
A method of authenticating a document (10; 36) or other article in which the article (10; 36) is sensed (18; 56; 106-112) for deriving an output that is dependent upon the translucency or other optically-related characteristic within a defined window area (16; 80; 132) of the article (10; 36), characterised in that pixel values (P1-P3; P1-P5) derived from the sensed window area (16; 80; 132) are weighted with respect to one another to enhance relatively the value or values (P2; P2,P3) derived centrally of the sensed area (16; 80; 132), and that said output is derived by processing the weighted pixel values (P1-P3) with one another.
Claim 2
Dependent Claim
21 words
A method according to Claim 1 wherein the processing involves additive combination (56; 118) of the weighted pixel values (P1-P3; P1-P5).
Claim 3
Dependent Claim
35 words
A method according to Claim 1 or Claim 2 wherein the weighting of the pixel values (P1-P3) is effected at least partly, by filtering (46; 54) light incident on and/or transmitted from the article (36).
Claim 4
Dependent Claim
30 words
A method according to Claim 3 wherein the filtering (46; 54) involves attenuating a beam (40) of the light outwardly (48, 50) of a central zone (52) of its cross-section.
Claim 5
Independent Claim
130 words
A method according to any one of Claims 1 to 4 wherein a beam (40) of light is directed to be incident within the window area (16) for transmission through the article (36) such that the light beam emergent from the window area (16) has an intensity dependent on the degree of translucency of the window area (16), the intensity of the incident beam (40) and/or of the emergent beam is attenuated differentially across the cross-section of the respective beam to enhance the intensity of a central zone (P3) of the cross-section relative to the intensity of at least one surrounding zone (P1, P2), and wherein said output is derived in accordance with the intensity of the emergent beam as conditioned by the degree of translucency and the differential attenuation.
Claim 6
Dependent Claim
33 words
A method according to Claim 1 or Claim 2 wherein signals in accordance with the respective pixel values (P1-P5) are derived from sensings made at different locations within the window area (80; 132).
Claim 7
Dependent Claim
49 words
A method according to Claim 6 wherein the signals derived in respect of the different sensing locations (P1-P5) are weighted relative to one another by the application (116) of multiplication factors that are dependent respectively upon the relative positioning of the sensing locations (P1-P5) within the window area (80).
Claim 8
Dependent Claim
32 words
A method according to Claim 6 wherein the sensed locations overlap one another within the window area (132), and the signals derived from the sensings at those overlapping locations are summed (118).
Claim 9
Independent Claim
46 words
A method according to any one of Claims 1 to 8 wherein the correlation between said output and the result of an earlier sensing of the article (10; 36) is determined by comparison (62; 120) of said output with the content of memory means (64; 122).
Claim 10
Independent Claim
119 words
A system for authenticating a document (10; 36) or other article, in which the article (10; 36) is sensed (18; 56; 106-112) for deriving an output that is dependent upon the translucency or other optically-related characteristic within a defined window area (16, 80; 132) of the article (10; 36), characterised in that sensing means (18; 46, 54, 56; 106, 116) derives pixel values (P1-P3; P1-P5) from the sensed window area (16; 80; 132) that are weighted with respect to one another such as to enhance relatively the value or values (P2; P2,P3) derived centrally of the sensed area (16; 80; 132), and that said output is derived from processing (56; 118) the weighted pixel values (P1-P3) with one another.
Claim 11
Dependent Claim
19 words
A system according to Claim 10 wherein the processing involves additive combination (56, 118) of the weighted pixel values.
Claim 12
Dependent Claim
41 words
A system according to Claim 10 or Claim 11 including filter means (46; 54) located in the path of light (40) incident on and/or transmitted from, the article (36), for weighting the pixel values (P1-P3) by attenuating part of such light.
Claim 13
Dependent Claim
41 words
A system according to Claim 12 wherein the filtering means comprises one or more filters (46; 54) having concentric sections (48,50) that increase in light-attenuating property from one to another outwardly of a central section (52) of the filter (46; 54).
Claim 14
Dependent Claim
33 words
A system according to Claim 10 or Claim 11 wherein the sensing means (106-112) derives signals in accordance with the respective pixel values (P1-P5) at different locations within the window area (80; 132).
Claim 15
Dependent Claim
63 words
A system according to Claim 14 including means (116) for weighting the signals derived by the sensing means (106-112) relative to one another by the application of multiplication factors that are dependent respectively upon the relative positioning of the sensing locations (P1-P5) within the window area (80), and means (118) for deriving an output dependent upon summation of those signals as so weighted.
Claim 16
Dependent Claim
39 words
A system according to Claim 14 wherein the sensed locations overlap one another within the window area (132), and including means (118) for deriving an output dependent upon summation of the signals derived from the sensings at those locations.
Claim 17
Independent Claim
40 words
A system according to any one of Claims 10 to 16 including means (62; 120) for comparing said output with the content of memory means (64; 122) to provide indication (66; 124) of the authenticity of the article (10; 36).
References Cited (Backward Citations)
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