Classifications

• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/30—Individual registration on entry or exit not involving the use of a pass
  • G07C9/32—Individual registration on entry or exit not involving the use of a pass in combination with an identity check
  • G07C9/37—Individual registration on entry or exit not involving the use of a pass in combination with an identity check using biometric data, e.g. fingerprints, iris scans or voice recognition
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F18/00—Pattern recognition
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
  • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
  • G06V40/12—Fingerprints or palmprints

Definitions

• the Matcher device of this invention in ⁇ volves a number of major components which operate together to provide the total decision making in iden ⁇ tification that is appropriately termed matching. More parti ⁇ ularily, the Matcher has four separately scaled comparator segments which are integrated "so as to provide a variable scale matching function. The Matcher also includes a scorer mechanism. However for the Matcher to operate to provide decision making, it must also have a storage for the File minutia points and a storage for the Search minutia points. It is a combination of all of these components that constitutes the.Matcher.
• Q is used in-different contexts with different sub-scripts to generally refer to how tightly various points are bound to one another. It is a measurement of relative proximity. Is is roughly analogous to spatial peaking, with reference to space on the difference plane not on the image plane.
• Q ⁇ will refer to a measure of how close ,two points on the difference plane are to one another.
• Qs will provide a measure of how close a par ⁇ ticular point on the difference plane is to all the rest of the points in the difference plane.
• the measurement Qt will provide an indication of how close to each other are all of the points on the difference plane. But generically this measurement of proximity on the difference plane will be referred to as Q.
• QT is used herein, particularly in the FIG's., interchangeably with Qt to mean the same thing.
• a third difference table is established based on the corrected Search point positions.
• the third difference table is screened for difference table entries representing Search and File points that remain further apart than a predetermined number of pixels and is also limited to a predetermined number of entries based on those having the highest proximity values in the purged difference table.
• This now more limited (fourth) difference table is used as a basis for recalculating the proximity values for each entry therein. These recalculated proximity values are used as a basis for scoring the comparison to determine identification.
• FIG. 3G I FIG., 2. To facilitate understanding the transition i from one of these components to the others, FIG. 3G
• FIGS. 3A through 3F shown in each of the FIGS. 3A through 3F.
• FIGs. 3H and 31 show a varient on the FIG.3A-3F embodiment in which correction factors are provided in the Y axis as well as in the X axis.
• FIGs. 3H and 31 correspond to FIGs. 3E and 3F respectively *
• FIG. 3J illustrates four points in the image plane. These four points are the File Point and Search Point pair S' and F' which has the highest Q value on the difference table. .
• Another two points illustrated are a difference table pair Sk and Fk which are being compared to the pair S 1 and F 1 respectively for the purpose of calculating the scale factor components SXT and WYT as indicated at operating box 38a of FIG.3H.
• FIGS. 5A and 5B are flow charts indicating scoring techniques which are employed in connection with the FIG. 2 comparator to provide ID verification.
• FIG. 5C is a table of the Q values of a perfect match as a function of difference table line entries.
• FIGs. 9 and 10 illustrate one known optical scan technique for generating the fingerprint image from which ..File and Search points are extracted.
• the matcher 10 compares the contents of the two memory units 16 and 18 in the manner described hereinafter to come up with a score which indicates verification.
• the set of points in the File store 13 may be de ⁇ termined in any fashion. However, for purpose of minimizing both the type I and type II errors, it is preferable that the set of points in.the File store 18 be derived from the same mechanism which derives the set of points in the Search store 16. -
• FIG. 2 An understanding of the ' block and function diagram of FIG. 2 will facilitate following and under ⁇ standing the more detailed flow chart arrangement shown in FIGs. 3A through 3J.
• the image plane X and Y values for the Search points are shifted to make the Search and File point pair S 1 , F' for the highest Qs entry on the purged difference table coincident.
• This shift is made by making the DX and DY values for that first entry S 1 , F 1 on the reordered purged difference table equal to zero.
• the same shift is made to all the other DX and DY values thereby effectively shifting all of the Search points Sk by the same amount.
• the Search points are further relocated based on the scale factor. Speci ⁇ fically, after the above shift of positions, the DX and DY values in the reordered purged difference table are corrected by the scale factor. It should be noted that in the simple embodiment of FIGs. 3E..and 3F, only the DX values are corrected by the scale factor. - The scale factor operates so that the larger the value for DX or DY, the greater will be the magnitude of the relocating correction. Since the value for DX and DY has been set to zero at stage 40 for the difference table entry having the highest Qs, the search point for that highest Qs entry will not be affected by the scale factor correction.
• the correction routine serves to shift and correct the Search points so that when the correct finger is presented for identification, the Search points are repositioned to be more in line with the File points and when the incorrect finger is presented the Search points tend to be shifted more out of line with the File points than they would be without the correction routine. Accordingly, the correction routine of this invention reduces.,both type I and type II errors.
• the Comparator Flow Chart (FIG.3A-Through 3G)
• An initial difference table is created based on a comparison of the set of File points in the store 18 and the set of Search points from the subject image in the store 16. Within certain limits, each File point JS is compared with each Search point IS in establishing the table. No distinction is made bet ⁇ ween line ending points and bifurcation poi ts. Each minutia, is treated as a point. A portion of such a difference table is illustrated in FIG.3B.
• FIG. 3B is a representation of a portion of a typical difference table. Each entry is given a line number. Each File point JS is compared with each Search point IS which is within the 61 x 61 pixel box centered on the File point. The X axis and Y axis displacements, DX and DY respectively, are entered in the difference table. The difference table is ordered by the Y value of the reference points. Because of the ordering of the JS and IS points in the memories 16 and 18 it is pos- sible, to include a loop routine which speeds up the comparison. Any Search point IS with a Y value below that of the window set up on a given JS, need not be compared with any subsequent JS points. Thus a deter ⁇ mination that the Y value of an IS is below the window means that the next IS point can be immediatel " re ⁇ viewed.
• FIG. 3B indicates the routine used to cal ⁇ culate the Q value for each entry on the difference table.
• the Q value for an entry. is the value Qs. That value Qs is the sum of individual values Qc.
• Each individual value Qc is based on a comparison of a given difference table entry with one other difference table entry.
• a high Qc indicates that the two entries- are relatively close to one another on the difference plane.
• the two difference plane points are compared by taking the- difference between two DX values and adding that to the difference between the two DY values to obtain the TR value, as shown by the equation 24a in .FIG. 3B.
• This TR value is then sub- stracted from a constant KR, which has the value 15 in this embodiment, to come up with the Qc value.
• the index "c” indicates how many lines are to be purged out.
• the index "s” indicates where a retained line entry is on the D.T. after purge of one or more other lines.
• the count c of line entries to be eliminated is incremented by one. as indicated at 3In and that line entry is placed at the line 256 as indicated at 31p. Placing a line entry at line 256 effectively eliminates that line from the D.T. since the number of lines ST on the D.T. is always substantially fewer than 256 and thus that line will be eliminated at the function box 322.
• the purged difference table then goes through the Qs calculation procedure of FIG. 3B and then is ordered by the new Qs values as shown in FIG. 3C.
• the difference table entries are provided at D as a basis for the calculation of a scale factor CO-7 as indicated in FIG. 3E.
• the Search point represented by the highest Qs entry on the purged difference table is deemed to be co.incident with the corresponding File point represented by that same entry on the difference table. That is, they are deemed to be coincident on the image plane. With respect to each other entry on the difference table. all other Search points are deemed to be displaced from the corresponding reference point because of distortion. A correction factor is calculated to reflect that distortion.
• a correction factor is calculated to reflect that distortion.
• the decision box 39r is significant only during enrollment. It is an enrollment flag. During the enrollment procedure described hereinafter the deletion routine provided by the buffer 45 is not undertaken. But for immediate purposes this enrollment flag 39r can be ignored.
• the appropriate correcting scale factors COV, SIW, COW, SIV are set to values of one and zero as appropriate and as indicated in the two function boxes 39y.
• KR is set at the value of 7. When this is done, it has been found unnecessary to include the decision box TR:KHR.
• an array of information is provided that permits a routine of determining which IS points are not represented after the purge routine has been completed. Then an appropriate line entry from the original D.T. can be selected so as to include a representation of each IS point in the purged D.T.
• FIG. 6B the criteria shown at 38d in FIG. 3E is not employed and thus those Search points having relatively small XI values are used in the FIG. 6 embodiment.
• the shift correction shown in FIG. 6C at 40a is the same as in the FIG. 3F embodiment.
• a window is created around the shifted and corrected Si point. This window is created on the image plane.
• the window extends 5 pixels in both directions along the X-axis from the Si point and 20 pixels in both directions • along the Y-axis from the Si point. If the corresponding file point Fi falls outside that window, then the corresponding line entry is dropped from the difference table by the technique shown in FIG. 3F.
• the X axis is divided into four segments and the zone associated with a segment extends along the entire Y axis.
• the Search point stores do not overlap.
• each Search segment is compared against a corresponding File segment in a separate comparator 17a through 17d, which comparator is essentially the device illustrated in FIGs. 2 and 3. Specifically all of the units shown in FIG. 2 from the compare and screen unit 20 through the calculate unit 50 are replicated for each of these four comparators 17a through 17d.
• the four segments illustrated in FIG. 4A are vertical segments which break the image up along the X axis into four zones which overlap along the X axis. Because of the overlap, each segment covers somewhat more than one third of the image.
• a fingerprint card provides the set of Search points that are to be compared with the set of File points
• somewhat greater flexibility with respect to time is possible and. much greater control over alignment may be provided. Accordingly, in such a system, the amount of overlap between the multiple segments may be appreciably less or if alignment is adequately controlled, there need be no overlap.
• An important aspect of the system of this invention is the segmenting of the fingerprint image into a number of separate zones and the application of the comparison techniques and matching techniques to each zone or segment separately. This multiple segment arrangement is described in connection with FIGs. 4A and 4B.
• the scoring techniques illustrated in FIGs. 5A, 5B, and 5C are scoring techniques which use the quality scores from each segment of the matcher.
• FIG. 5A is a flow chart of the operation of one of four scoring units. Each of the scoring units are coupled to separate outputs from the four separate comparator segment units 17a through 17d. Thus the particulars of the following identification technique is based on the four segment embodiment of FIG. 4A. If any one of the four sets of ouput parameters meets the verification critera set forth in FIG. 5A then identification is verified. This is a quick procedure when there is a high degree of correlation between the Search points and File points in any one of the four segments and avoids going through the FIG. 5B routine.
• the inputs to FIG. 5B are the outputs from each of the four FIG. 5A units presuming that the I.D. has not been identified in any one of those four FIG. 5A units.
• a combined final matcher segment score SQ is calculated that takes into account not just the individual matcher segment scores SQ n but also the mutual matcher segment scores SQ mfn determined by the relationships between the four matcher segments taken two at a time.
• the calculation of the individual matcher segment quality score SQ n is shown at the operating box 50b in FIG. 3C.
• the combined quality score SQ from the various segments of the matcher is calculated in a fashion that takes into account not only the quality score for each segment SQ n , but also the relationships between the quality scores of each segment.
• the SQ m n value between any two segments if added to the SQ value ' for each of the two segments being compared equals the SQ value for the two segments combined and considered as one segment.
• the product of the two ST values provides the factor to represent the additional pairing that would be possible if the two segments were considered as a single segment.
• the product of ST for segment m and ST for segment n provides an appropriate factor that exactly makes up for what is lost by segmenting where there is a perfect match.
• the two proximity value ratios (QT ratio) provide the appropriate down grading of the SQ m n contribution.
• FIGs 5A and 5B may not be required. It might only be necessary to rank a series of quality scores SQ (as calculated in box 52b) so that the Files for the top predetermined few are pulled for further investigation. In such a situation, the Search record is compared against each of a predetermined number of Files, selected for some fingerprint type category, and those having the largest SQ values selected. In such an application, the I.D. thresholds shown in FIGs 5A and 5B would not be employed. Enrollment (FIGs 7 and 8)
• the value of the Matcher is greatly enhanced by having an appropriate and effective enrollment procedure so that the Pile points include a reasonably good number of repeatable classical minutia.
• the enrollment techniques shown in FIGs. 7 and 8 are of appreciable importance.
• the automatic enrollment scan technique of FIG. 7 will normally provide a good usable enrollment File
• the manual enrollment technique of FIG. 8 can be employed when it is desired to generate the enrollment File on the basis of an enrollment officer visually picking out points to provide the enrollment File.
• a point in the initial en ⁇ rollment file is deemed to be matched in any one of the subsequent enrollment scans only if that initial enrollment file point appears in the limited dif - ference table developed from the output of FIG. 3F. Because no ID verification is involved, the subsequent calculation of values such as Q ⁇ need not be under ⁇ taken. However, processing in enrollment does re ⁇ plicate the processing in verification up to the point where ID verification steps are required.
• a single scan is taken and the extracted points are presented to the en ⁇ rollment officer who goes through a point by point procedure of selecting or rej-ecting the extracted points. If the enrollment officer selects forty or more points, the enrollment procedure is ended and those forty or more points become the File. If the enrollment officer picks fewer than forty points, the enrollment officer can execute an additional scan to provide an additional set of points for review.
• FIGs. 9 and 10 indicate a known mechanism for optically scanning a fingerprint to provide the modulated- light beam input to a CCD array 77. Since it is described in the issued Patent No. 4,322,163, the disclosure here need not be in great detail. Suffice it, therefore, to say that a beam of light such as may be provided by a laser 66 is appropriately collimated by lenses 68 and 70 to provide the inter ⁇ rogating beam 71.
• a substantially transparent platen 62 is provided as a base on which an individual finger F may be placed.
• the platen 72 is mounted in a movable carriage 74 which permits moving the finger across the interrogating beam 71.
• An encoder element 78 which is affixed to the carriage 74 responds to movement of carriage 76 to produce a synchronizing signal each time the carriage moves a predetermined distance.
• the synchronizing signal causes the scanning circuit 80 to sequentially interrogate each of the photodiodes comprising the array 77.
• the output of the scanning circuit 80 is a train of pulses for each scan line. Each pulse represents a picture element or pixel.
• the input to the array 77 can be the modulated light beam that is produced from a scan of a fingerprint card or the direct scan of a finger positioned in space without a platen.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Human Computer Interaction (AREA)
• Bioinformatics & Computational Biology (AREA)
• Data Mining & Analysis (AREA)
• Evolutionary Biology (AREA)
• Evolutionary Computation (AREA)
• Computer Vision & Pattern Recognition (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Bioinformatics & Cheminformatics (AREA)
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• Multimedia (AREA)
• Collating Specific Patterns (AREA)
• Image Analysis (AREA)

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• 1986
  • 1986-04-01 KR KR860700856A patent/KR880700362A/ko not_active Withdrawn
  • 1986-04-01 WO PCT/US1986/000635 patent/WO1986005903A1/en not_active Ceased
  • 1986-04-01 EP EP19860902617 patent/EP0216902A4/de not_active Withdrawn
  • 1986-12-01 FI FI864881A patent/FI864881A7/fi not_active IP Right Cessation

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