EP0744716B1 - Method and apparatus for authenticating documents - Google Patents
Method and apparatus for authenticating documents Download PDFInfo
- Publication number
- EP0744716B1 EP0744716B1 EP96303493A EP96303493A EP0744716B1 EP 0744716 B1 EP0744716 B1 EP 0744716B1 EP 96303493 A EP96303493 A EP 96303493A EP 96303493 A EP96303493 A EP 96303493A EP 0744716 B1 EP0744716 B1 EP 0744716B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- document
- discriminant function
- function values
- distance measurement
- representing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Revoked
Links
- 238000000034 method Methods 0.000 title claims description 24
- 238000005259 measurement Methods 0.000 claims description 11
- 238000001228 spectrum Methods 0.000 claims description 9
- 230000003595 spectral effect Effects 0.000 claims description 6
- 230000006870 function Effects 0.000 description 33
- 238000012986 modification Methods 0.000 description 8
- 230000004048 modification Effects 0.000 description 8
- 239000013598 vector Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000003086 colorant Substances 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 238000003909 pattern recognition Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
- G07D7/12—Visible light, infrared or ultraviolet radiation
- G07D7/1205—Testing spectral properties
Definitions
- This invention relates to a method and apparatus for authenticating documents.
- U.K. Patent Application No. GB-A-2 192 275 discloses a system for authenticating banknotes by detecting colours thereof by reflected or transmitted light.
- Optical fibre bundles direct light from a light source onto the banknote, and the reflected or transmitted light is incident on a plurality of colour filters which pass the light they transmit to respective further optical fibres which transmit the light to respective photosensors.
- the output signals from the photosensors are analysed to determine the authenticity of the banknote, by comparing data representing the detected signals or signal ratios with corresponding reference data derived from a genuine banknote.
- This known system is based on a comparison technique and has the disadvantage of requiring the storage of large amounts of reference data.
- a method of determining the authenticity of a document comprising the steps of: dispersing light derived from an area of said document into a spectrum; generating a plurality of electrical signals representing light intensity values in a corresponding plurality of spectral wavebands in said spectrum; and storing data representing said electrical signals; characterised by the further steps of: analyzing the stored data by calculating discriminant function values utilizing the stored data, determining a distance measurement representing the distance between the calculated discriminant function values and reference discriminant function values, and determining said document as authentic if said distance measurement is less than a predetermined threshold value.
- FIG. 1 there is shown a simplified block diagram of a document authentication system 10.
- a document 12 whose authenticity is to be determined, is fed by document transport means 14 to a sensing station 16, where the document 12 is maintained in a stationary state for a time sufficient to sense the document in a manner to be described.
- the document could be placed manually in the sensing station 16.
- a broadband (white) light source 18 which directs a narrow, collimated beam of light over a light path 20 to illuminate a small circular area 22 on the document 12.
- Light from the area 22 passes via a light path 24 to a spectroscope 26 which disperses the incident light into a spectrum output beam 28, in the wavelength range of from 400 to 900nm, for example.
- the spectroscope 26 may be a standard, commercially available spectroscope.
- the dispersed light beam 28 is applied to a photodiode array 30.
- the number of photodiode in the array 30 may depend on the application. In one example, 50 photodiodes are produced, thereby producing electrical signals representing incident light intensity on a corresponding number of output lines 32, which are connected via respective amplifiers 34 to a multiplexer 36.
- the number of photodiodes 30 is not a limitation, and more, or fewer, than 50 photodiodes may be utilized.
- signals derived from a relatively large number e.g. 250, of sensors may be compressed by using a computer program to a smaller number, e.g. 50, of points per spectrum. It is found that good classification results may be achieved with as few as 15 spectral points, for example.
- the output of the multiplexer 36 is applied to an analog-to-digital converter 38 which provides, on a serial output 40, digital data representing the light intensities incident on the respective photodiodes of the photodiode array 30.
- This data is stored in a memory 42 which is connected to a processor 44 which processes the data using the statistical technique of discriminant analysis, in a manner to be described, utilizing reference data stored in a memory 46, and provides an output signal on a line 48, identifying the document 12 as genuine or counterfeit.
- the processor 44 operates on the data in accordance with the statistical technique of discriminent analysis. It is assumed that the documents being tested for authenticity are all of the same document type. For example, if the documents are banknotes, it is assumed that the banknotes are all issued by the same issuing bank and are of the same denomination, for instance, the documents 12 may be Bank of England ten pound notes. It will be appreciated that if the apparatus 10 is located in a machine capable of accepting various types of banknotes, for example, then an initial recognition step may be required to recognize the document type, and provide a signal to access the appropriate reference data stored in the memory 46.
- Samples of the particular document type e.g. Bank of England ten pound notes
- banknotes of three classes namely genuine notes, colour photocopied notes and forged notes (other than colour photocopied notes) are available, wherein forged notes have been produced by printing procedures more sophisticated than colour photocopying.
- 200 genuine notes, 100 colour photocopied notes, and 15 forged notes were utilized, although these figures are not a limitation and other numbers of samples may be utilized.
- the colour photocopied notes and the forged notes are examples of counterfeit notes. All the sample notes are fed in turn to a sensing station, similar to the sensing station 16 (Fig.
- the technique aims at "projecting" the points in the high (e.g. 50) dimensional space to a lower dimensional space which is of a dimension one less than the number of classes, i.e. where there are three classes, to two-dimensional space, while retaining a high degree of clustering, corresponding to the original clustering.
- functions are computed which maximize the ratio of between-class scatter to within-class scatter.
- the projection from 50-dimensional space to 2-dimensional space is accomplished by two discriminant functions.
- a procedure for computing discriminant functions is set forth in the aforementioned Duda and Hart textbook reference, for example.
- each sample note gives rise to corresponding discriminant function values (y 1 , y 2 ) in 2-dimensional space.
- the next step in the procedure is to calculate the mean (centroid) discriminant function values for the genuine notes.
- Fig. 2 there is shown a plot of discriminant function values (y 1 , y 2 ) for the various sample notes.
- the discriminant function values for the genuine sample notes are shown as small solid circular areas; the discriminant function values for the colour photocopied sample notes are shown as crosses; and the discriminant function values for the forged sample notes are shown as small outline circles.
- the discriminant function values are disposed in three clusters 60, 62 and 64, corresponding to the genuine sample notes, the color photocopied sample notes and the forged sample notes respectively.
- Fig. 2 is simplified by not showing the full number of discriminant function values, for clarity. However, the clustering of the discriminant function values in three clusters 60,62 and 64 is clearly seen.
- the mean (centroid) values (m 1 ,m 2 ) of the discriminant function values for the genuine notes in the cluster 60 are calculated and stored. These values are represented by the point 66 shown in the plot of Fig. 2.
- a threshold value T (to be explained) is entered and included in the reference data.
- This reference data may now be transferred to the memory 46, contained in the authentication system 10, Fig. 1 for testing the authenticity of an unknown banknote.
- the reference data may be stored on a diskette which is transported to the location where an authentication system 10 (Fig. 1) is installed. Copies of such diskette could be utilized to transfer the reference data to any locations where an authentication system such as the system 10 is situated.
- a comparison is made as to whether the calculated distance is less than the threshold value T, included in the reference data. If yes, then a signal is produced on the output line 48 (Fig. 1) indicative of the document 12 being authentic (block 92). If no, then the signal on the output line 48 is indicative of the document 12 being counterfeit (block 94).
- the distance comparison effectively determines whether or not the point on the plot corresponding to the document 12 being tested lies inside the circle 96 having centre 66 and radius T. If the point lies inside the circle 96, then the document 12 is determined to be authentic. If not, the document is determined to be non-authentic (counterfeit).
- the signal on the line 48 may be effective to return the document to an entry slot (not shown) or divert the document to a reject bit (not shown). If the document is determined to be authentic a transaction can be performed. For example, if the document is a banknote, a financial transaction may be initiated.
- the number of classes of documents may differ from the three classes utilized in the described embodiment (genuine, colour photocopies, other forged documents).
- there may be four classes new genuine banknotes, used genuine banknotes, colour photocopied banknotes, other forged banknotes.
- new genuine banknotes and used genuine banknotes produce respective clusters of discriminant function values which overlap, and the mean (centroid) of all these discriminant function values is taken as the point corresponding to the point 66 (Fig. 2) from which the distance is measured during the authentication procedure for an unknown document.
- the circle 96 (Fig. 2) is replaced by a sphere and that authentic documents correspond to points within the sphere.
- the distance measurement used to determine the distance between the discriminant function values of a document being tested, and the centroid discriminant function values is the standard Euchidean distance measurement.
- the Mahalanobis distance could be used in which case the decision curve or surface, corresponding to the circle 96 or sphere, discussed above, would be an ellipse or ellipsoid, with a document being characterized as authentic if its calculated discriminant function values correspond to a point inside the ellipse or ellipsoid.
- the concept of Mahalanobis distance is well known to those skilled in the pattern recognition art. For example, see page 24 of the aforementioned textbook by Duda and Hart for a discussion of the Mahalanobis distance concept.
- a plurality of such small areas for example three such areas, located at different points on the document being tested may be utilized.
- the light source 18, Fig. 1 may be controlled to direct light successively towards three different small areas of the document 12.
- three small areas could be sensed simultaneously. The data dervied from each area would be utilized to provide an authenticity signal, and the three authenticity signals would be utilized, for instance using a majority voting procedure, to categorize the document as authentic if at least two of the signals were indicative of an authentic document.
- This modification will result in an increased amount of data to be analysed by the discriminant analysis procedure, but more reliable results may be achieved.
- the document 12 may be sensed while it is moving. This will require an appropriate control of the photodiode array 30 to provide signals corresponding to a desired small area or areas to be sensed.
- light could be directed towards and/or sensed from the document by using optical fibres.
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Inspection Of Paper Currency And Valuable Securities (AREA)
- Character Input (AREA)
- Collating Specific Patterns (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB9510678.7A GB9510678D0 (en) | 1995-05-25 | 1995-05-25 | Method and apparatus for authenticating documents |
GB9510678 | 1995-05-25 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0744716A2 EP0744716A2 (en) | 1996-11-27 |
EP0744716A3 EP0744716A3 (en) | 1996-12-18 |
EP0744716B1 true EP0744716B1 (en) | 1999-12-29 |
Family
ID=10775074
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96303493A Revoked EP0744716B1 (en) | 1995-05-25 | 1996-05-16 | Method and apparatus for authenticating documents |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0744716B1 (es) |
JP (1) | JPH0916777A (es) |
DE (1) | DE69605854T2 (es) |
ES (1) | ES2140787T3 (es) |
GB (1) | GB9510678D0 (es) |
ZA (1) | ZA963604B (es) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7899233B2 (en) | 2003-06-17 | 2011-03-01 | Hitachi-Omron Terminal Solutions Corp. | System and method for tracing bank notes |
WO2017185141A1 (en) * | 2016-04-29 | 2017-11-02 | Ccl Secure Pty Ltd | A method and system for identifying and measuring a defect that reduces transparency in a substrate for a security document |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH09231435A (ja) * | 1996-02-21 | 1997-09-05 | Copal Co Ltd | 紙葉類真偽識別装置 |
JPH11154253A (ja) * | 1997-11-20 | 1999-06-08 | Sanyo Electric Co Ltd | 紙葉類の真偽判定方法 |
FR2846445B1 (fr) * | 2002-10-29 | 2005-04-08 | Claude Lambert | Procede d'authentification par marquage ou tracage chimique d'un objet ou d'une substance. |
DE10346636A1 (de) | 2003-10-08 | 2005-05-12 | Giesecke & Devrient Gmbh | Vorrichtung und Verfahren zur Prüfung von Wertdokumenten |
DE102009058438A1 (de) * | 2009-12-16 | 2011-06-22 | Giesecke & Devrient GmbH, 81677 | Verfahren zur Prüfung von Wertdokumenten |
DE102009058439A1 (de) * | 2009-12-16 | 2011-06-22 | Giesecke & Devrient GmbH, 81677 | Verfahren zur Prüfung von Wertdokumenten |
CN102254370B (zh) * | 2011-06-17 | 2013-05-08 | 深圳市怡化电脑有限公司 | 纸币宽度和间距检测及张数统计的方法及其装置 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4526466A (en) * | 1983-09-01 | 1985-07-02 | Rca Corporation | Technique for verifying genuineness of authenticating device |
WO1985002928A1 (en) * | 1983-12-27 | 1985-07-04 | Bergstroem Arne | Apparatus for authenticating bank notes |
US4577235A (en) * | 1984-08-20 | 1986-03-18 | The Mead Corporation | Text/continuous tone image decision processor |
JPH04346187A (ja) * | 1991-05-23 | 1992-12-02 | Matsushita Electric Ind Co Ltd | 被検出物の良否判定方法 |
DE59208542D1 (de) * | 1991-10-14 | 1997-07-03 | Mars Inc | Einrichtung zum optischen Erkennen von Dokumenten |
-
1995
- 1995-05-25 GB GBGB9510678.7A patent/GB9510678D0/en active Pending
-
1996
- 1996-05-07 ZA ZA963604A patent/ZA963604B/xx unknown
- 1996-05-16 DE DE69605854T patent/DE69605854T2/de not_active Revoked
- 1996-05-16 ES ES96303493T patent/ES2140787T3/es not_active Expired - Lifetime
- 1996-05-16 EP EP96303493A patent/EP0744716B1/en not_active Revoked
- 1996-05-21 JP JP8125352A patent/JPH0916777A/ja active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7899233B2 (en) | 2003-06-17 | 2011-03-01 | Hitachi-Omron Terminal Solutions Corp. | System and method for tracing bank notes |
US8155423B2 (en) | 2003-06-17 | 2012-04-10 | Hitachi-Omron Terminal Solutions Corp. | System and method for tracing bank notes |
WO2017185141A1 (en) * | 2016-04-29 | 2017-11-02 | Ccl Secure Pty Ltd | A method and system for identifying and measuring a defect that reduces transparency in a substrate for a security document |
GB2563168A (en) * | 2016-04-29 | 2018-12-05 | Ccl Secure Pty Ltd | A method and system for identifying and measuring a defect that reduces transparency in a substrate for a security document |
Also Published As
Publication number | Publication date |
---|---|
EP0744716A3 (en) | 1996-12-18 |
JPH0916777A (ja) | 1997-01-17 |
DE69605854D1 (de) | 2000-02-03 |
GB9510678D0 (en) | 1995-07-19 |
ES2140787T3 (es) | 2000-03-01 |
EP0744716A2 (en) | 1996-11-27 |
DE69605854T2 (de) | 2000-07-20 |
ZA963604B (en) | 1996-08-23 |
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