SE543667C2 - A method for comparing a sample comprising fingerprint information with a template - Google Patents

A method for comparing a sample comprising fingerprint information with a template

Info

Publication number
SE543667C2
SE543667C2 SE1950074A SE1950074A SE543667C2 SE 543667 C2 SE543667 C2 SE 543667C2 SE 1950074 A SE1950074 A SE 1950074A SE 1950074 A SE1950074 A SE 1950074A SE 543667 C2 SE543667 C2 SE 543667C2
Authority
SE
Sweden
Prior art keywords
ridge
points
sample
curvature
point
Prior art date
Application number
SE1950074A
Other languages
Swedish (sv)
Other versions
SE1950074A1 (en
Inventor
Marcus Andersson
Original Assignee
Precise Biometrics Ab
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Precise Biometrics Ab filed Critical Precise Biometrics Ab
Priority to SE1950074A priority Critical patent/SE543667C2/en
Publication of SE1950074A1 publication Critical patent/SE1950074A1/en
Publication of SE543667C2 publication Critical patent/SE543667C2/en

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR 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
    • G06V40/1347—Preprocessing; Feature extraction
    • G06V40/1359—Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR 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
    • G06V40/1365—Matching; Classification
    • G06V40/1376—Matching features related to ridge properties or fingerprint texture

Landscapes

  • Engineering & Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Collating Specific Patterns (AREA)
  • Image Input (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Display Devices Of Pinball Game Machines (AREA)

Abstract

A method (900) for comparing a sample comprising fingerprint information with a template. The method may comprise determining (902) an average ridge curvature vector of the sample, and comparing (904) the average ridge curvature vector of the sample with the average ridge curvature vector of the template, wherein the average ridge curvature vector is determined by identifying at least one ridge in the sample, determining the curvature vector of the at least one ridge in a plurality of points of the at least one ridge, wherein the curvature vector is a vector whose length is proportional to the how much the ridge is bending and whose direction is pointing inwards towards the focal point of the ridge, calculating an average of the curvature vectors of the at least one ridge in the plurality of points of the at least one ridge.

Description

A |\/IETHOD FOR .\\ fx. .-*NGM Technical FieldThe present i: _=__generally relates to field of biometric verification and identification technology. More specifically, it relates .-\.- .w-w-M- \-.-\ .-\ -\.«;.-\-“. =..\ m. eva-Var. \-\-\~~=\-\= =.« S, \-.-\-\.-\§I_.-..~ __«: “- ...s _~\ _-..\\.\¿ N . M ;_. A - _. ¿. .w _ .~\-_~ - \-\ _-\ _» i \»\.\_-\ .w _. F. \\ _.~\ qfi N _. _ .W wow; vw.w .«.....»\.\.- .os ~ \.»\- _- »nu U. oc: :__-M .vu .-- M ~.~~M\_».\~~..\..- - ._. 4 t BackgroundFingerprint authorization is today part of an everyday routine for millions of people worldwide. lnstead of using a PIN code for accessing theirmobile phones, people use their fingerprints for verifying that they are therightful owners of their mobile phones. Another example of biometricverification technology is modern payment systems. By having a templatestored on a smart card, a user may authorize a payment by placing his or herfinger on a fingerprint sensor. After having captured an image of thefingerprint, often referred to as a sample, the sample is transferred to thesmart card where a comparison with the template is made. ln case thesample and the template matches the payment is allowed, otherwise it hasnot been confirmed that the user is a rightful card holder and no payment isauthorized.ln its simplest form, a biometric verification system comprises a sensor, e.g. a fingerprint sensor, for capturing the sample, a memory forholding the template and a processor for comparing the sample and thetemplate. ln many applications, e.g. when biometric verification is used in themobile phones, a display is used for providing information to the user.Further, as exemplified above, to reduce the risk that the template is undulyspread this may be held in a separate device with processing capability, suchas the smart card. 2 A common way of matching a sample with a template is to identify anumber of points of a particular type in a sample and compare theirdistribution with the distribution of points of the same particular type in thetemplate. Typical points which are identified are so called minutiae points,such as an ending or a bifurcation of a ridge of the fingerprint.
During the last twenty years the demands on biometric verificationsystems have increased continuously. An acceptance level for false positives,i.e. incorrectly stated matches between the sample and the template, as wellas an acceptance level of false negatives, i.e. incorrectly stated non-matchesbetween the sample and the template, have been lowered. At the same time,the size of images used for matching purposes have been decreased suchthat these images only cover a part of the fingerprint. This is a consequenceof that a size of the sensor which acquires the images is smaller today than afew years ago. An effect of having small images is that less biometricinformation is made available to the comparison. This in turn has led to theeffect that minutiae point matching is in many cases not sufficient, since onlyfew or no minutiae points may be available in the sample. This may then alsolead to the matching procedure taking significantly longer time since a samplemay need to be captured a number of times until one with enough minutiaepoints can be found. Therefore, in order to provide for that a reliable and fastmatching is made, new technologies specifically addressing the challenges ofsmall sensors have to be developed.
Summary lt is an object to at least partly overcome one or more of the above-identified limitations of the prior art. ln particular, it is an object to provide amethod for determining a key point in an image of a fingerprint which isreliable and fast for images of a small part of a fingerprint. _ _.. “- _.\ “w _ MW _.\__.\~ \__ \ _... ,. _ _._\\ __\ .__ _ .N . W _. . ___:\__ ___ _ _ ___-_» »N A _ ~ w 3 ___. _.. _. 3 I_.\ï ... __. i å. IE ___ »N *___ __. _._ .s r... ...r . ._._x.s... ..v _....... _. .-.;...5 .-. _...._. ..._.. z-j.. .-. _... ._..-.â-\ ...1.rs r r\-s t.. .r._r r. \»x. s sx.._r rx-§ ... . . r s..»_s r r\.s .rr \. _ _» .r~ _. _-. _ ..-s .-. .-. S š-w _.. .r. _..ä f. .-.... . ... _-._ s... s.. _ . ._..s... ...r -... .x_. .v- .-._. .f - ~..-\:.-\§ -x \-\.-rr.v\.-\_srš .s\.'\ r~_r\.~x .v\. .rrr .rwr-.rs .ç-rsrwvx s ._s... _._.\;_.. ._.¿.._ ._. ___._._....__._. _.._..:_....s. :.;..... ...___ _____..;_..._... .. _ .r_.x.».s ...x.v x.v..-.x.s... .s .~. . _.. . . xax... .s\-_\.x.\. fx.. x s s...s ...s . . ..- x.v... .r _x.s..-r. .x ..\. __. . . s x.vxr .rx .r s..KI. ._-.-§§...-._.v .-. !.~_«.- _- _. .-.§...»_s ...-;.-.__v i.\.-. .r-.-..»_..»\.'_.-... ...š- _.. _. ä, _-_.-.-.:'E.\._. _.~..i. x.r. _.. . .v._ ...s r x_- x* _.. .r._ s. s__...s_ x.. .v .r...-._ .vr . r r.. _x.-_.. x.. _.._.... ...s-...v .s._.-' .q _. ...rs ' ...__tr:\r:š*.::§_.r.r_.._- ...s'_.._.. _.....».-.« i. ... ;_..:_......:_.:_. _.. ..... _... _.._ _... .<.._.._.... _..... ..._.....s'_. _.._...._~ _.. _.. ;..§.r.. __.._.._...~__.._.. :._. _.... _- ..rx..\v ... _- ....rx.s._._.r... .r x..... .x.« ....rr ._ _-_.. ._.__ _-._ ...__ _-._ r. .r. x.«.r...s..s...r.. _-.. __...\.- .r r ..-_.-._. .rz-...v . .-..- =.-....:_...- _-... _...:_. __.-_.-..-.._v.......\.\r r..« \.r.r\.r. wF* rx.^._\.r\.~.\r sk \.-. ss“.rs\.r. »'\»Sxr\.r.r r. s* - r' ' s : s s . . _ s _ : _ _ -. _. .r .vx _-\; r .v. _. .v\ rr: r .v .vx .~\ r* .r švx .- y; .vx .- r .w :vxvxcxr .v .rrs .vx .v\s »r . .v\_r .r ;r .vx . x .v\ ~'\ - r - r r _- .vx _-\r .r rx..r....r x.« ...r .. ...f _ _x..\.x.« . . m.. r r _ __. . _x.. ...\_ ...r . x .r....r . x.. . rrx.. ...~...r 'Tiw . ....r-.-..^\ .-\š- .-.f.-.+.-._...._..E.-.E.-\.«\ _... .-.. ._..~- . ....r. ...s_. _.--.r Ivíx .-. .-'..~ =.-._. 3.. _-\ _~-~.\}.-.-_r .-.-..-._ _. ~~...- x-x .vx.- ..-.s x.. .r. .s. ....s~..ss... ... .~x.r. \^....x.s...- .r. _... .~ ss... __... .sr x.. _.sxv..ss. .s....._\r ..« ... ,_s..._'... '........I_É. _. Ü... ._I.'r“\_~' _..“...... ._“..É.'r“\.r .rf .. .-\... ...-_«s.\ .....s.\_-- \ .\_.\_. .. ._....s m.. .w ___: _\... s _- -_.\.x_ n. . ...\...r .__ . _.. _- _.x.s..-r _ ...w .\.x.» x.. .~.x.v. _ . _.. ... w.. ..._\ s.s \.s. ..^..-.s s.. . . ...r s... ... .x. .~.....-r s... _.x.».s s.. . ... ..-r -_.x.v._ _ _ _ _ . . .__ . ._ _ _ .~ .\_._~..._.\.«.-x.-.«x .r.~x.«\ ;.;.-.~.~.~ _.\....~\r »x.-..~\.«\_~-x_^\r ;. .-._.«.>:. ,.~..~'_«\ ;. .-.«\_-.~;_«\;.~;.-x.«\r _.\~.~\ .r\r^\.~\-s..._.-. .~_~..~\r.-.~. +x«._.\ .-.. s. ...r ._« _.. .r._«.._.x_-. _ _-._. .s- . ._._x.-__« .v._-.s....~ .s...x_. .v._. x _ .ss._. .ss..«. .-.s r .rr..« .r. ...x ..._ sx.. ..- .vx_-~._«_ _x.\ _.. r '.“\- i. _. "_". _ . _ . rr. "_ r. . '_ '“* '. . __ _' __.~..-\_.-\¿ ._.-. _ v\...s_\.-_~\-\..v...vx.-\ .-; _... ..-.. rnr- \«~ .»..-\s...-\ .vx .r.\-\ _.».v\..vxr ...s- §-\_-._v..-\_-š .._. ...A_.x.s..... . x-v. x.. f. .«.....rs.rs§_. ..-. .x-s. ...x .r rr... s... .rs .rr..- _. rs. s .s x.v..-.x.s... _. .~.. _... .s.-.r'E .-..s.-._-x.»\ _.. .. s. .-..\. _. .-._.. =$.. ..._. 2,... 51): .six . r; ...-..\ _... ...E ...5 :IIS s: .~..-._..= 51.. _... .-._. 2 ......I.-.= í§3^ .r.\.....s~. .v .v._« x.. .v..s\^... .v.. _... .v _x_-..._..s. . ......- s.s\.. :.sx_.sr. r r x..._x.. .H .v \.x....~...~.... _.rx_.r~.. . ..._' z =-\ s ~-~-~»-~ -\ -\ ...s r-r .r -x~- rr .-..-'“s v-rš sr-ï-r -x ...rä-x »s š-w sr-r s-r .risr ~ *w »-»-s.s ...w .så '._I- r." _-x.-.r ss. . rr...' .r....«_\\.rx.- x.rx.s'.r r.\.r. .x^. . .r. x. .\.r .. 4:. .r x.sx.-'\\ \r .rs r .rr-.sr .s.r\.\ ä . . \.\. .\.r .r. .v»._. f... p; .«.r ...__.._ _..._x .__ . _. .~\...«. _~ s.. _.. ...s _ .\_~._.-_....; .~. _. __.. _.. _..__..r . _. q.. ..._.. _ . _.. vr.. .«. .».»_r..._. __...x _. . ..._ \.».~x».. _... _.. _.. v. x.s._.~ _. _.. _-.__._ :__ rr_x.s_ ._. _- _....~~. . _...rr._.~ _._. xr.. .s .-.r.. _-. ...-r.. _- v. _-:.. ._.x.«..._._ rr_r.._.._._r x.. _.._ -..-.....r-_ ._... ...s- ss... .-= s_.-... ..-. .rz-w. _. .-...-.._. s___=_v'r. _...._..._. 5. _..-.r-_.-_ ._.- _. .-. s..,.-_.-..._.-: .-._.. 5.... _.-.~_.....~.,..._.._...-.wiwflr \.\\.v_r \.r \.- r xr r-.f _ \.\ «}\.r r. .r \) .r\.~ :v Or. .r. r .r r r r\.\}* . \.\. \. .\ sv v \.'\.\\» \.r -vï .rr . . s s .r .r.\. \x.~.r r .ri... .r. _...._. _.. s.. _. .~... .».. ...._~.-.=-~ Wrisr ...w .s:.. _. _. _..;...._. Qjgær,_ -r\.s S x..'.r r \r r\..' _ . r\.\\.r\.^ \.^\.s _ .'\\.^r .\' s .v ..~_\\ u ~r \.' .'\.» :v .rs _ Fx r -r . 2 .~x_v .v\r ~.~'. _ s\.~~ ..-u\ .r r' :år v ~^~.~\r-s~.~\ .r^r rrvrv .v -^r.r^r>{^ .__.rs . .~\~\.r\r .r :vrr-*x vxrßrrê-*r r\v\;.~\ v vr' år r .r »s s r rx.~' l år x.\\..v.r \.s x.s r .s s-.C _ _\.\ «§\.s s. .r \.r .rxø :v .rs_ .rx r .r s r r\~\}r . i \.\ .'x\. s . . s.r r ..»' .\ x-s r' x-v..rI..... _. i. ... . .- 2-1. . . '- r.{*\«\ . _ .r r ~\'.'“ . ...'.... f... .~. 2-1. . í'_«.š . ' r.?*\»x'\..\..\.^\r\s\ .\~\.\.r..r .\r\ .\~\ \\.' r.^\\ ha. ^\\\." r . .r \ss;~\x\.\\.\ .r.\\\ .\~\ \r. \_ \\.' r \r ...r .x_..x.s.x.x.. .x.» ... _~..s.r.._- .«.. _... . x._.c.. rx.\..»..rs§.¿ ....-sr. __.. .s .r...~.. _x.».._r..x . _ _._..._r. .x _ ._ ..._\. ...r i.. .-. _.. _.. _.. ... _.. _. š ... _.\§ “i. . .v ..x _.. .s- ..._ _.-....~ ... -. / \.-\ .~\~\ .~\ _r\ .~i _.. .w .vx .\r.rï.\r.~x.v\r -\ sx-x- \*~§~r.-\_-r.rr x.»..-r_._.^x_.. r. . .s x.. ..x.. ... . . ....-xr r..- -s .-. _. -...._ _.\.~._..» _..-..~.. .vw ;.\ _... ...x.» ... ..- .v .»..- _ rx.. ... .. _.. ...-x.s. . . . .. _.-s ..- .s _... _r'\ »x .vr .r\ w-rš . rrr .rx .r.r _ .sx.sx... ..._ rxq .._ .. _.. i _. š ...ï _.._x;_. _. ___' _.. _.. _...._. : _. __. _.. _.... _. ..; ..§ _.. __ _ .r _ ... _.. _.. _.-_. ..C _.. .r. _' ....i... _.-_...._.._ .r-ï _.. _.. . _. _.[ .r.'... _.. .r. _.. _...._.\š _.. :.__ .x-\~s...:..r...~ .v _r..~_.._ r..».rs¿.. r.. r... _-.:..__..r. s... .r. ..s...x.x.s._ .r.rsr.__ ... x .v..~_._~_\_x._..-. x.»...rx.. __. _~.rs... _..-....-.._.-...-I..»;_~...-. .r-.-._.~.~\..}.-.I.-._-\ ..-_.r- S.-._-..-.».r- ....-. . I __.. .r-j... -.......-..-.$.-. _-._.-. -..-._.~_.\::_.._.-. .r-_.-. .r-L....r.\«'\ .rr ..r\_rrr. .r\.\ \.-\\ r .r\.\\~\ \.r .r\.r r r.. \. .\ \.r\.\r.r.\.rs .r \.\ s »r .rr \.-\.rs Q \ ö \..\.r ._- _ x.vx.-_ _.:_s. .\..s. . _. __:_ _.. _. .r. _.. _. .». _.\__._.~_ _.. .få _.__.._ ...xt _.. __ . .r-ï.. _. _.._... -__-g __...i __._.\ 5 _.._.._ ....r. _.\... _. i. _... _ ... _. ;_...r. _ _... .r-L. _.. ._~... _... __.. s __._.\_...r...~r. x_x..~__-x.» xx. xf: ..sx.. -rx_ss\. x. s _.. -x.ssr.. -rs ...x . .-x..x-x ..»_ r... . __ _x.s...r..r. s.. s .x.s...:.rr...x _-_ _.._.-....-....,.-...-_.-._-. =;...-. .-... .-.;_v._. .-. _-..- .s\-._. ,.-..s s.-..-..-..r- _. .-._. -..-.._ ..._. '._.-..r- _.-. .r-l-.f -...~~.-.-....;.-. ...r-M.. .s\-._._.. . _x.-...s..x ...s ..s.s..- ..-...-s.s_x.-.x- _.-..ss .ss._- ...- .s..s_._-...- .. .s.. .~ _x.v._-\..s.s...s ~ ..-.s .ss..- .... .v._.\.. ...s ~._- _. .~ _ ._ ....-....:_<;_. _.. .».=- .».§ :_. _.. -g .»._..... :.»..~.» ....-._..._< n.. 5 r . » ._ r.. _.. .- _.. v... _»\; “_ _.\__-x.v.x.r.s...r r x.s_ x_x.. r...~\~sx.... \_«. . _- » x.. _ rx_s.r r. _. . . x .v. . ._._._x_x..x... :.._. .._...-..\:.._...-.r' ...»..~.-_- 1, _...r.z...-\_.- _.._..._..-._.._.-:.._. ,.-. _-..s.-._.. _...rï _.. ........_....; _.. _.. .six . ...-. .-_.._.\. \»r s x-\ \ .r r x.^ rr... __. .v.rr... .r »rrxxy _..._ x__x.-_ _..~ .s. . n... _x.-...~ ._. x.x .vx.« ... r ..«'...r s _x.-._.s r. .x.r .. ...vr r . ..- rrvršwx \.\.r;\\šv\ .r.vx_-_ __.. . .. ..._- _ _: ..._ _.. _. ._ _.....__\\.- r \-\\ r ~'\.\..-_\ \.r. !\.r _..:. _.s.._. ___... ;__._......~. _. _.._. =.-.~... .-._-~v._.~..r~ J-. .s:-..-. -..-_..~...x.x w.. ...f .x .r _ _x.. _-s. .x ._r xr r ..- v... s s r_x.» . x.» s_... . . ..._. 2,... _... .r-r... _.. .s _.. ...\_»~.:_....~.-.\\. . . s: årx-\\ .'. . _..-_ _.-.......s. ...x “f l~r x .r\-\.- ärr» .rm-rr .vvr .sx -5 . . .ri-Im .sx .r-r .-\_-\ .vvr .vx .ss .-\ _-\ -r ru- .vx .-\ r' xr - .r .rx .-r.s\-\É .vx É vr .w ._._-šv\ .- š-rrr xrr S É-x -rxs ..x.» ....._-...._...r .x.\. .«. .....-sr_x.s. .\.x.. ... .._.x.._-_..s x.». x_..... .~. ....r ..r .._. ss...-.__..._ ._.. ._ _ ._ »vx mr" .rívx -.. . ...- _.__.. _.-_.. _ _.. __\_._ _.. _. L.. .r.__.. .r.:.._ _.. _. _.. _... _... : __.__\ _.. ;.._.._ _.. _.. _. t __.. _. __. i.. _ _._.r_ _.. _. _.\ .r. _.. \ __... ..._.._ ..; .._ _.. _.. __\.._. :__-rr sx.v.\. \ -r \. .\.^ x\.^. . .. -'r\.\\ -r k \.\\-\.^x.». .rs s xs s«..' .\-\ .'_x.~ \.v.r x.sx.vr .r __\.r\.\.r rx.v -rr s \.v.r .x- ms. . .:.. r ...- According to aš aspect it is provided a method for comparinga sample comprising fingerprint information with a template, said methodcomprising determining an average ridge curvature vector of the sample, andcomparing the average ridge curvature vector of the sample with the averageridge curvature vector of the template, wherein the average ridge curvaturevector is determined by identifying at least one ridge in the sample,determining the curvature vector of the at least one ridge in a plurality ofpoints of the at least one ridge, wherein the curvature vector is a vectorwhose length is proportional to the how much the ridge is bending and whosedirection is pointing inwards towards the focal point of the ridge, calculatingan average of the curvature vectors of the at least one ridge in the plurality ofpoints of the at least one ridge.
The plurality of points of the at least one ridge may be positioned onthe same ridge.
The plurality of points of the at least one ridge may be positioned in a sub-area of the sample.
Brief description of the drawinqs Embodiments of the will now be described, by way of example, with reference to the accompanying schematic drawings, in Which Fig. 1 is an illustration of a ridge skeleton image of a part of afingerprint showing portions of a number of ridges.
Fig. 2 is an illustration of a ridge of a fingerprint showing a main pointand a first and a second point situated on each side of the main point.
Fig. 3 is an illustration of a ridge with a number of points marked, oneof them being the extreme point.
Fig. 4 is an illustration of a ridge skeleton image of a part of afingerprint where a number of key points of ridges have been identified.
Fig. 5 is an illustration of a ridge of a fingerprint showing the mainpoint, the first and second point and a mass point.
Fig. 6 is an illustration of a ridge of a fingerprint showing the curvaturevectors of two points of the ridge.
Fig. 7 is a first flow chart of a method for determining a key point in animage of a fingerprint.
Fig. 8 is a second flow chart of a method for comparing a samplecomprising fingerprint information with a template.
Fig. 9 is a third flow chart for another method for comparing a sample comprising fingerprint information with a template.
Detailed descriptionFigure 1 shows a ridge skeleton image 100 of a part of a fingerprint which has been acquired by way of example. The image 100 comprisesridges, herein illustrated with black lines. As illustrated, the ridges are ingeneral curved. A bifurcation 102 of a ridge, i.e. a point in which a single ridgesplits divides into two ridges or two ridges come together into a single ridge, ispresent in the image 100. Further, an ending 104 of a ridge is also part of theimage 100. A ridge can be defined as extending between one end of the ridgeand another end of the same ridge. An end can be defined as an actualending of a ridge or the bifurcation of a ridge or where a ridge meets the edgeof an image or any combination of these definitions.
A ridge skeleton image is an image of the ridges of a fingerprint whichhas been thinned and binarized. The thinning of the ridges can be such that 6 the thickness of ridges is one pixel. The skeleton image can be made suchthat the bifurcation never splits into more than two directions.
As illustrated in figure 1 by way of example, there are just twominutiae points in the image. Due to limited information, it will therefore bevery hard if not impossible to identify or authenticate someone based on thisimage if only using minutiae point information.
Figure 2 illustrates a ridge 200 on which a first point P1 and a secondpoint P2 have been determined. The first and second points P1, P2 are eachsituated on opposite sides of a main point P0. The main point P0 is the pointin which the curvature of the ridge is calculated. The points P0, P1, P2 are allsituated on the ridge 200. The first and second points P1, P2 can be situatedat an equal distance from the main point P0. The distance from the main pointP0 can be defined to be along the ridge 200 or the distance from the mainpoint P0 can be defined as the absolute distance from the main point P0. Thecurvature of the ridge in the main point P0 can be calculated from thedistances between the points P0, P1, P2. For instance, this can be achievedby using an angle between P0 and P1 and an angle between P0 and P2.Alternately, by using distances between P0 and P1, and P0 and P2. Still anoption is to use a distance between P0 and a center mass of the curve. Thecurvature can be calculated by comparing the absolute distance between themain point P0 and each of the first and second point P1, P2 with the distancealong the ridge between the main point P0 and each of the first and secondpoint P1, P2. The curvature can be calculated by comparing the absolutedistance between the main point P0 and each of the first and second pointP1, P2 with the absolute distance between the first and the second point P1,P2.
Figure 3 illustrates a ridge on which a number of points has beendetermined, illustrated by circles. Of these points, an extreme point has beendetermined, illustrated by a larger dashed circle. For each point, the curvatureof the ridge in the point has been determined. The extreme point isdetermined as such because among the determined points the curvature ofthe ridge is largest in this point. The points can be chosen such that they are 7 at an equal distance from each other. This can be an absolute distance. lt canalso be a distance along the ridge.
Figure 4 illustrates another skeleton image of a fingerprint with anumber of ridges. A number of key points of the image have beendetermined, illustrated by circles. The key points which has been determinedhave been determined by determining extreme points of the curvature of theridges. For some of the ridges one extreme point has been determined. Forone of the ridges two extreme points have been determined. For one of theridges no extreme point has been determined. None, one or more extremepoints can be determined for each one of the ridges. The positions of theextreme points form a pattern which can be used to identify or verify thefingerprint. ln other words, for determining the key points a number of points ofthe ridge, herein referred to as the main points, is evaluated. The main pointsidentified as extreme points are considered key points.
Figure 5 illustrates a ridge on which a first point P1 and a secondpoint P2 has been determined. The first and second points P1, P2 are eachsituated on opposite sides of the main point PO. The points PO, P1, P2 are allsituated on the ridge. The absolute distance between the first point P1 andthe second point P2 is shown as a dashed line L12. The mass center l\/IO ofthe ridge segment between the first and second point P1, P2 has beendetermined. The curvature of the ridge in the main point PO can be calculatedfrom the distance between the main point PO and the mass center l\/IO. Thecurvature can also be calculated from the length of a line which is normal tothe line L12 and extends between the line L12 and the main point PO.
Figure 6 illustrates a ridge where the curvature of the ridge has beendetermined in two points of the ridge. The ridge curvatures have beendetermined as vectors and are illustrated as such. As illustrated a length anddirection of the vectors are related to the curvature and direction of thecurvature of the ridge.
By determining extreme points as described above, minutiae points may be replaced or complemented with these in order to increase a number 8 of points used, herein referred to as key points, for identification or verificationpurposes.
With reference to figure 7, a method 700 for determining a key pointin an image of a fingerprint will now be described. ln this method 700, the keypoints which are identified are points on a ridge where the curvature of theridge is at a maximum. The maximum can be a local maximum of thecurvature of the portion of the ridge which can be seen in the image or theglobal maximum of the curvature of the portion of the ridge which can be seenin the image.
The method can start by identifying 702 a ridge in the image. Afterthis step, the curvature of the ridge can be determined 704 in each of anumber of points of the ridge. After this step, an extreme point can beidentified 706 among the number of points. The extreme points can bechosen based on the curvatures of the ridge in each of the number of pointswith the point where the curvature is greatest being chosen as the extremepoint. The extreme point is the key point.
The position of the key point can be extracted. The position of the keypoint can be used for determining how the fingerprint images are to be rotatedand translated with respect to each other such that a comparison between thetwo can be made.
For the method 700 a number of key points can be determined. Thekey points determined can be one for each ridge of the image of a fingerprint.lt is also possible to determine more than one key point for a ridge. Forinstance, it is possible to use local maxima and/or local minima. ln addition tokey points on the ridges, minutiae points may be used. lt is possible to have a predetermined number of key points which aredetermined. The key points can then be determined to be the predeterminednumber of points of the ridges of the image where the curvature peaks. lt is possible to determine key points as being points with a curvatureover a certain threshold. This can be for all points or for all points at a certaindistance from an already determined key point. 9 The image of a fingerprint can be a ridge skeleton image of afingerprint. Each ridge of the fingerprint can be thinned and binarized.
The ridge can be identified by scanning the image of a fingerprint fora starting pixel of a ridge and when found the ridge is followed until it ends orbifurcates. The coordinates of the pixels of the ridge can be saved in order tobe able to identify the ridge.
The curvature of a ridge in a point can be determined by determininga first and a second point of the ridge which are situated on opposite sides ofthe main point. The first and the second point may for instance be placed 12pixels from the main point. lf using a sensor with another resolution a greateror smaller number of pixels may be used. The first and the second point canbe determined such that they each are situated at an equal distance from themain point. The distance can be the absolute distance between the points orthe distance can be the distance along the ridge.
The curvature of the ridge in a point can be calculated as a vector.The direction of the vector in a main point can be determined by determininga direction given by the first and second point. The two normal vectors of aline between the first and the second points can be calculated and thedirection of the curvature vector set to be the that of the normal vector whichpoints away from the main point of the ridge. The length of the vector in amain point can be determined by calculating the mass center of the ridgebetween the first point and the second point. The distance between the mainpoint and the mass center is then calculated and the length set to that value.Alternatively, the length can be determined by calculating the length of a linebetween the main point and a line between the first and the second point andthe length set to that value. The line whose length is calculated can be a linenormal to the line between the first and second point.
With reference to figure 8, a method 800 for comparing a sample witha template each comprising fingerprint information will now be described.Such a method 800 can start by determining 700 at least one key pointaccording to the above described method 700 for determining a key point.The position of at least one key point of the template can then be extracted 802 and the positions of the at least one key point of the sample can becompared 804 with the position of the at least one key point in the template. ltcan then be deemed 806 if the sample and the template correspond to eachother. lf the positions correspond to each other the sample can be deemed tocorrespond to the template. lf the sample and the template correspond toeach other the fingerprint of the sample can be deemed to be that of thetemplate.
The curvatures of at least one key point of the sample can becompared to the curvature of at least one key point of the template. lf thecurvatures correspond to each other the sample can be deemed tocorrespond to the template.
The above described method for comparing can be combined withanother method for comparing a sample with a template comprisingfingerprint information.
With reference to figure 9, another method for comparing a samplewith a template comprising fingerprint information will now be described. Sucha method 900 can start by determining 902 an average ridge curvature vectorfor the sample. The average ridge curvature vector can then be compared904 to the average ridge curvature vector of a template. lt can then bedeemed 904 if the sample and the template correspond to each other. lf theaverage ridge curvature vectors correspond to each other the sample can bedeemed to correspond to the template. The average ridge curvature vectorcan be determined by identifying at least one ridge in the sample. Then bydetermining the curvature vector of at least one ridge in a plurality of points ofthe at least one ridge and calculating the average of the curvature vectors ofthe at least one ridge in the plurality of points. The curvature vector of a pointcan be a vector whose length is proportional to how much the ridge isbending in the point and whose direction is pointing inwards towards the focalpoint of the ridge. The length of the curvature vector can be calculated in thesame manner as the length of the vector of the curvature described above inrelation to calculating the curvature of a point in a ridge as a vector. Thedirection of the curvature vector can be calculated in the same manner as the 11 direction of the vector of the curvature described above in relation tocalculating the curvature of a point in a ridge as a vector.
For all of the above described methods the plurality of points of the atleast one ridge can be positioned on the same ridge. The plurality of points ofthe at least one ridge can also be positioned in a sub-area of the sample. lt is possible to construct an apparatus comprising a processing unitand a memory which processing unit and memory are configured to performany of the above described methods. lt is possible to construct a computer program which comprisesinstructions which when the program is carried out by a computer cause thecomputer to carry out any of the above described methods.
From the description above follows that, although various embodiments of the .§_:;g~3___have been described and shown, the not restricted thereto, but may also be embodied inother ways within the scope of the subject-matter defined in the following claims.

Claims (3)

1. CLAIIVIS _' .s -: ' .i _ ä .~\ s^s“>'st_«\.~s~-'\' t \s- :s-xs-vs-s s_-\s_^\.~s ._ ._-_- s. s_-\ _\ss ss\~\.~~-s~s 'st vs_. _» sr. »___ _s_._ __.-. _.__.-..\_-..~...__.__ »_ \..\s _.-_s .__ _._.~s s.______.~ _ .~_ \.x__. .s _.-=";_-._-_ _-=.__=- .-__-_}.-.= _-___.-_=_I~_.-__-= __.-__»_____ _-;__;.-__«_._..~_._ _~~~.-..~____ \.\.__ ._ _____-____ »___ .«__-__-..~__-_.~s_.___- s ~ s __«.___-___ '___ =-_»_.__ '___-___-_ .___._ »__ _« ~______\__..___.s -få.- ss-ssv' \>\_sss_;-*s_>\ .s\ _-\s s_»'_ _~._\__'~; ~_~.~\ .»\_'ï :íss- sss.:\=_- s.~\ __» _»_.-s;_~sí>\ _~\s" ex ;-\s s:-\'\É- vs; _'\s" v\_-s_';-s\\-\»___-_ _~______s____._ ___ .s ..s~ _._\_._s__~ _..s _~~_._ ___._\___~ __: \_«_._ .sm __.s ___ ___ ___._. _ __.,- _.. _____\.__§___.-_ _s__»ss .-_ ___s_«_«_»_.\. _«___\§___<- ____«_-~.-____.-_ _. .-_§_-__s___ l«__«\.~.-.s__~\= _. _~\:__ _ _.__. _.s\_.__...~ ,.~__«___s. ___.s_. :__ _ _.. .~_.__\. _.>____\_. .___ _..s~ §;._ .-_ .-__ ___.. __.-_ _s_ _ .-._-_ - -.s__ .____-_- .__ -_s:__ _ .-_ __-_s_- »__-__ .-_ _-____š ____*- _ __» =_;._ .-_ t_- ._- _- __» .__ _-__s_.__ .s :\.\. \:\._\_\.s_ z\_s_ \\__ _ss\_s_~_ _ss__«' .st _*\_s.._ v _\.s_.-.\__\ sx- .___ .~ \ \_s)* __*\>_.\\__rs. *s.“;__ ___ _ __._:.;__ ___: ._ ,_______\,.___=; “___ ___ _._3 __; V... _- _ __ :_-_..___ ___. :____~_ ___..c.. _ . _ _ _« _ s ~_.v.._ _ »__-_ _.-___»_..__-s _\_s »___ _._.- _._'_\_\_ s s . s _ \ ___ __ _~ _ ___._.-s_ __ ~_\__ _ _ __ _ _ _ _. _ _ _. . ____ ___, __ ___ ___.__._ _. _._ ___._ ___. __.. ___ _ ___ .-___«_ _ _ .__ _ :___ ___«_ __.-~__x_..~_ _ _~_ ___ ___-_ .s_ ____s _. _ _«_ s s_._§._ ...__ _Q '3"¿._ .__§i___.__ __.= ___ __-_.-.~_' ___... ___. ___._._ _ _._._ _. .___ ___., _.~___ ._- ___ .___ .__:.__: _.___ ____.. . __ .~ ~.s_ _-.__ :___ ___ __-__-. .~-.__.; ___- ____.s_ _ _ _ __- _~-___- _.~-__-_~.__-_____ .~~___.s.____«_____-Ia .-_ ___ ... _-:_-_= ;.._ = _= .-_.__=~::“-; .-__-_= _~-,___ ___ =ï_~~______._ __ _._ _-_= .-____' ___ z- _-___- :___ g. __--,__.-.-,_: .___-_ _~_.-__^\*__ :_ ._«'\__ __«_\ '.'\.-\ .§__- _\. .\.\ csnusšx .'\.-\ _.~_\_' \ J .\\.*\_ .\\.s\.\. _.~_ss _53 \\.-\_\.'\.s.s\\ \.-_ _«^.\_\.\_ 1__«_\_.\\.s)\ \ ö _«s;_~\,~ +å-~_s\\- _ _-\_- s_-\_«\š_«\š- _s\_- :WMR __s-_»ss.-_-_s'__«\_-_ _._s~____.~.~_.-. .._-s~__»___.-_.-.~__\ _.-. __^.~__._. .~\.s_s_.->s_a' ““§__ _ _ 'Åß _ i _ . .Üï _ _ 2- »_ . _ _ _ i å: _ _ _. * . _ sw' ~_«______ _ “__ _._.__.\__;___. .___ __. _ _\__\.v\ \ _- _\ . .»\_~.- -' s __-\__ ___. . __.. __ _ \ .\_- __ _._ _ s _ _\_s _ _ __.. :__ _\_«_._ _...\_.«_..__- s \_\_ s »___ ___.. ___» _ _' _...s s__.~ __. w _._ _ -s .\_s_ ___' _ s_.. \~s__~ __«__...\s.' _ -«\-: \ .s :ïss .s\ _* -s_ sss *Ls .s\ _ ~ ;_~_ __ _~\ V; v* ~'\ _s\ s' \\Ä~s .s i-*å *sç .N v\ _ -\ .~\3 vs _* .'\ vsssïs v\ -ss v\: -'\ N -*s _ _- .s\ _-\ s'<.s\ s~_ _< _ _'\ _ _' \.' .'\_* se \_\' \_\__\_\P \_^ \_^ _ \\ '\_~' _ _ _\š_} \_^ \__. \_\ _\_s _ _' _ __ s _ \_\ \_\\- __..\ _ \ '\\_.! ___" “~“$._ .-_ .-_-__-_= $._ .-_ _-_s f» .-__-__-\ _-.-_*I _-_ _-_ 3 _ »_ _-_ .- -_s .-_ _ »-_._~_- - :i _- - _-_ .-_E ._-U_ »___ _____ _ _ _ .~ - s .~_.-.._ _ .s_._ _.__.»_.-__-. ___. :___ __.- ___: s _ _- ~ .__~ _ .s- __- _» ._.-_.__.~ _.»-_._s . _ ________-Ia .-_ *___-_ ___. .-_ .___-___ .-__i __-:_-_=__ ___-_: __._:_-._ _-_ .___ ___ _.-_ =_ ___-__ _-_= m.. _ ___; .-.=___ .-_ :___ .._ _:.__:_ .-__-__-.-__-_ ___^\'__ vx ~\«'\_ _ X__ v \_'\\.':«' J! ~\<3\_'__\_s'. *Pfix _)\ _ \-\ \_'\.\) _ \-\_-\.\. _' \.'_ \. \.s ss JÄQ .' Ps _ _.~_ _\.'\.-_\ s__ \.'\.-.\___ Os \\.\.'\_^_~ _- \_ _~~s _ p; vx .-\ ¿ _ ;.~ -\ L _-\ ,^“ \ _~~s-_\ _-' sQ \“ s _s\ v; ~~\' .s\ -\ sss \.-\ _s*s v\' e *s _ _s*s\\ s; ~~\' :w v\\_\\\_,\__\\_§ \-\ _\___-\ :__ _'\_,\ \5 \; \«\__ A ___ __. -\_»\_v_.\_\ :v )\__\ __ .\§_-A\\_»>_ _ _ _ _ _ _ _ _ _ - _ _ ; _- _ __ __ .sïss .s\ v* vs _ »s _\s~s .s\ _*s :f -\ s~ vx vs v\' ~\ - vs _~\ z-s; m* _'\_-s _ _s~s_\ .-s; _» .»\ _'\_-s ~s_ ss; -s \ vs vx' .- _~\ _~\ sss _'\ s» vs» ~~_- -\; v\ -ss vs -*s _ sflss .~\_ _ __ s _s :___ _s_ __.:. ___. ____ __»_..____«_ _ __ _.. _ __ __ _._s __~ _.. . _.~_ :__ .-_ _ .___ __. _ _ __._ .-___~ _~__~_ ____.~ __.____ .___ __ ___ _ _ __. :___= __ ._.____: _._:___ ___ .___- _.___ =_ ___-_ ___? _sz_. .__ :_-._ :___ .-_ ___. :___- __= 335m :___ = _.~_ __ »fi-_ .______-.s_.s_ :__ _ _._ __-____ .-_.______. .v _ . _____- .s_. .v ____...s___\. _. .-. _._._\. .___ :__ ___...-_. _ _. _ _ _-.__. _. .__ _ . ___.____ _ _ __ _' __»__ .-__\.-__~\ ->.-_ -_ _-_.-_-,s____-__ »__-_ -»_~_.-_ ___. ___.__- _~ ;_}_\\ -»___.-_ _s_._ -w _-\_-\;_-\_ . :___ x *_ _ ~ -_._ _.__.__._ __, _,.__.__\._\.x__ .s .»_.- _.- .~_ ___- .»__ .___ .s __.-_._.~__\ _. .A13 .___ .s ~.s_.-_ _.:_.-.s~.. _\_ _ __ _.~.~___-_ _.-_.- .s .»__ .s __.-____~__\___ ___., _ _ _ ._ _. _ _ _ _ ; _ _ __ _«_ __ ___ ___ ___, .___ .__ __ _ __. _._ ___ ___; “___ _._. __ _ _ .___ __. _. _. _ _._ _ ___ __. ___.___. ._ ._ _ _._ _ _. ._ _ _ _._. _ __* _ _' _ _\_^ _ \ \\_s !__ _\_< ___ __-.\\_* \_s'«_- ' \_\_ s wšfi __\_. \-'_ \\ \ _ .'\ \_» _ \ _ vu _ _' ' _' _\~.\\_~\_v sdwf* \ _-\_: _ \ P _< _ -' lf ___-i .__:._ _ __: _._=__ ___ 5. ___ ___ _. _.. ...___ .~.'___ __. __: __: ___ :___-_ __' s __ ___.. ___ ._ _. ..___~. ___* _. _..s _____.~ ___._ _\._ __. _-___s_..\_s__ :___ _- ___ __... ___«_..___:. __ _ _. _...\__ .s ___\_s _.s_..~ .-\_«__ __ _.. :__ _.- _ _ . _ .~-.-__~_-»_-_§ ___ ____.-.s ___-___: _ _- _-š-_ »___-_ §___ 5$._ .-_ .-__s.-____ _. S ___= .-_5_~__. .-_._§ _-_§_~__._ _-_ .___ ___-_ ___-___ .____-_ .~_ _ _ ___ :___ __. -___ ___: _s_~_ _ ___ ___-__ _ ___ _ .v _ .:___ _.. _ ___ .-__._. _. ..- _.- K., ___; __-_._. _» _.__\__.-. x* .vx _- ss .-x; .~x ~ s» .vx -x _» .vx' _-x vx x“~.~x .vx .-\s- -x ; .vx w . .-x 1- _~x yx _x _' - .vx _.. _... .vx .'-x-x_-\ - v _» _~x ex x* »x .-~ .^ .. Ö.. \_\x\ \\.- :«\.vx\ s._ x-'\«\x.- -\.\ x.-.! x! !\.v x.x.x.>x\.x. .\.*x.- x.- .*...*..-\.vx . &. .\.v ..\x.x.\<\. _' n. .x cs \\~ \x.>_~ _.. .\:.. _.sgtšr. “r i-“C s “.“.«. .x _.._._. m.. _ ...t .-. ,.._.x _.. _-. _. . :-_. 2 .«.ï .-x~. _;“ . _~ _-š.. .-.__-_. i _-. z-j.. .-. .-.. _ ~ _. ....s. __-.- . c-j.. .-._* . s _ _\.s . x \x.~'\. .\. .vs \»\x.«'..~' ês \.\.s w... 3.... .Hx-x. w s s \.. x*\^ x x J» x.~'.*x . _.. . .' .'\.\. \* _.«_\x\.\\ x." ß. _ . .- _ . . . . __ _ _ _ . _ _ ...__. _~-~ _. -.. _~-~.\ _ _. _-\~.-.-, _. ..._ .s. .s z~ . _» _.-._ «.».- -..-x .x å-x; .-x ». .-. -,\.-. _ .-..._ .-.; .~ '...~.\_\ s-_.-x_- ~s. . :v ös. .\ *xv x.-x .'x\.'. . ...x . 1\.x xv. x.~. -Hx- \x.~.* sws' 1 \.'x.-'\\ \. s xs sxf _.*\.-.\ s. \\\ xu; x.\\ sxv. .x;.. __ ;;_.. _.. \_ ___; _ _; _. .x.__.. _... N.. __ __. _ _._. _.._.__ ..._.\. __.. m; _..§ _-x....- _~._ _« _- ...-_~s..s._ .s s. .~_.. x.....- . ..- _x_ _«...._s~x.. __-x_v.~s._ \\. .___-.-s\ _....,...-_.. _«._. . _. _. .~._«. h... _«. _.._ .vx _. . _... _.. _.. _... _... _ _ _.._«. _...._. _.. .._ _.. _. . .-_ _.. _.. ... _. _. _.. _.. ._.. ..~x.~._.. .-x.. .._.s .v _-_.....x~x..~._.. ... x.x.x__...~~__.~ .v .-_.....ssx.._~._.. ..s~._. .-.._.ss..s.- ..- - - ..- ..- -:_-...~ï_..._- ,-..._..=-; .-._-.. - ».; 5 5.. _.. e.. ._._..«.5 .-. 5 .x _«. _.; _«.= _.._._. .~.._._._..: __. _...._.-.__~; .._.:_.._. .s..~ .~~.~~x.._.. .-.. x ~_... ._. s.._.~~s_x.-.x.x.x_-_ x_-x.._x.. ...._.-x__x..._s _.._.v~._x._~.\. .v xš .~\~^~^\^\ï .'v\ï.~\_-*~ ME se H *i -^\.'v\ -^\ ïv vx* .~ .W -^xÉ M5 :vx Six v-s v-s-*x .wxv i v -sx .~\.v\.v\ v-*xšš “vx Søx .v*:~°\- . A5~ s .s. .s. _ _; x.._. s...-_._s.x_s. .-. . .- ~ x_- .v :.~x.-.s ~. _~ . _. . .v x.x.x. . .¿_.- ...- _.«s.._~..«~..«s ...s ~¿_. _.._« ._.- ~ x* ._«s -1 _...x _- .'~ _..« S_...~._.=« .-.... \ =__ _ ._ .v._-.:_..: ;_... :§.._~. .\_~x_»..._. :_...~__... __ _« . _«__._._~._.. _~_ .-._..=«;.._.. sa... _..-_~.' .s x.. ax.. .s. x. _ _« _x.. .-x.~.._. _-. . ..- ...x s -x.....x ..._ x.. . ___-_. _x_«..._. .__ »_ _ ._ ... .-. _. I .xt _.. _.. .-x_ .vx~x vx _-\ v". .W .vx__-x.»._.. ._ x.- _ s x_~ _ x. _x.» ...x x.v... x s _x_«x_.s s. _x_s ...s .-. _. :« .-._...-. ._ _~..-.:_..:- ;__- si-.. ....-._...._~.i... ..-.«E.\:... .~x.x...x .,._ sx.. _ .__-__ __«.,._. .__ s. _ x..x.v x.~x_xs_.__^. _~ .«.~.x__ .s- ä.. _.. _._vx s... _. : _.. .s. _.. . x -. -v... _.. _..__.. »._ v; _«. _..x. .x .x_«. . .:..sx..x .-. !.__x_^ __. .-x_~.s.. .-.. - _ .s _«..». -~..- _.. .-. _. . __ _... _u \.\«\- \ xq! \ x..' . \ f: “.“._. f. _.._._. .~_:_._._..: .-.,.._._... __... ~: ,_.-:-§.._ ._._-.- __._..._.-_._. _.. .s. »s:«._. ..:.. _.. _..$x.~_ ~ _ _x_- . . ....~x_ _x_ .._s x.x._«~...~ .s- x_._~ k.. x... ~ .x..__ . ._-..«s _ _, .-. .x.~. ...s .~ ~._.~ ..._ ._.-_x x. _ s-..-.,~.s._« .-._«~,v.-._«. =v_...-. .-.. _.-._..-._<. \-._1 h-.. _-.:- :_ .-._.=v :.-_« -,- .-...-.-.= ä.. =v_...-. .-._-.. . I I V x . . . .~.....-_._.\. .s s... _. .v x.-x.~_ .~\...x.~. .v .v. x. .x- x.xx ..«~x.x..-_. ..-.s ..^x.-.s ~_ _. .~ x.x.._ _...«. .vs x_« .x_\ .';x“~§~x x“~§~. .-\ _-\; ~ .-~. .~.-\ å. _.~ .vx _-\ å« .-\ å« å »x .vx -x 3- .-x _~~\ .x 2.- _- x _- x~x.-\; .-x§ s.'\ 3' x »x xM-x a-x-xfx: .-\ 5' -_ .s _ xs s xs s..- _.-'...s x_xx...~ x.v x.-s x_xx s -x_x..-._ x.»_ _x.v ~ ..-. _ .^..-_s .__ s. _ __. . _ x _~. . s;.-_x_x_x-.- - iv. - _-. -xsívx _- _«.* .vx _-\._.....;-«_..:; _... _.. s... .vxí .-..; _.. -i P. .'«_ ;.~.\:.. _. _. _. .. .v.-..»._.«t ..3 _.. _.. _... ....s. _.. _.. ...s-. ...f s._ .-...__. .. x_. .v ...s-__ .g x _- x_^~...~_.. _ :_ s...~ x~~._.~. _..~_..._.x_~.s~¿_. ... .x-x _~_..~ ...- .-.*. .\.-._.-_.._.E.«.;...,_. ..:«.,. .'-å«..~..- =$.. ...._...: . .-..-._-. .-.__._...__._. n. :-_. :-'..._.. »s_«.. ._...:_.._.~.-. \«._«..-._«._.
2..._.-. .v. . . ..s -._ så. - ~...-._ _x_-_ _.. . .v x.x.._ . _: s-...- .v .~. _ ._.-.._x_« s. ...... x... s._ x. .x_ _ . _: s-...x .v x.._.x.x_... .«. _~.$ _~._«..«.-..«..«..«:_.,. .«. _~..- ...__ 1.- .-... _».,. .__.:- __ ..(:-;.-._-.. _. .«. .\:«._. ..:-....s ~ .~ ~...~ ._.s.._.-_x.- x.. x_-._«s _ _,.v..._ s._«..«s ~ x.. .s s..« . _x_-..«s. .s. __ .vx.«.s.. .-. _... \* ."\, .~x e vx -x v .vx S . . -x _x~\ .- .-x _«~> .~x -x -xš .~x .w ç ~ .-x x* r; vx .-; vx. »x :x-mx vx _«~ ..v.- \x:.-_x_«._.s x_x..x_.... __-~ ..- _- _«..~..-.~ så.. ...~ ._x ...s ~x.x ... s. _ . ....s __ _ _.._. _. _.. _.. .. .._ _.. _.. _ _ ....; z _.. _.. ...š N.. _. .... _.. _...._.. ... _. _.. _.- _. _.. _.. _.. .'32 _.. _ _.._«.,. 2 z _.._x_-. __.x_-x.~._..x. _-~ ..._ .~ _. x... _ _. .s ~._.~ ._ _ _~. . m... _ ...u ._.~ .v _-. .s. s._.. f... _.x.»
3.4- .~x§.§._ _~x .vI_-~._~x~*\ Rv l-§...-. isxxsx--w. ..._.-~ -.~_ _ x.. .. .~... .v s. . .v s...... ...vwx_« ... v .~.-.__-_.._.;._._. _.-.... ___.. q.. 3... __.__.g.. _. .f ,.__..;.-...._.- _. .f _.-._.;..._.-. .v. ....s ~._.- __. .~x.~. x._..x.~. ._.~ .s. _.. . .v ~ ~... .;._.- .~ ~ ._«_._s.._-. . ._.~ ... _ _x.._ __.~ =.*x.-. x ex. .çx-xl- .~x.'-* _-..« .- _....~~.\.~. .~x_-x-.~.~..-x~ _- .~x -_*švx_-z. \. .\.v xx\-\.xn.- nu xu! :v .'\..\\« .«^\-\.\. ß\-\ .~\\\ .\\..-' _.._. _.. _..x..,......_ .~x_-.I_..;_ _.. ....__..\__x. _ .s x_.. _ _. _.^..-.. __. x... _ _ _-. . '._ :,....__ _.\_..,;__...x. _x.. _-._ _.. _ __ .-.~._..-._..-.. ,»~».».;.~.= :....- ; f method for comparing a sample comprising fingerprint information with a template, said method comprising \ “gan average ridge curvature vector of the sample, determining and comparing 1§-_}___the average ridge curvature vector of the samplewith the average ridge curvature vector of the template, wherein the average ridge curvature vector is determined by identifying at least one ridge in the sample, determining the curvature vector of the at least one ridge in a pluralityof points of the at least one ridge, wherein the curvature vector is a vectorwhose length is proportional to the how much the ridge is bending and whosedirection is pointing inwards towards the focal point of the ridge, calculating an average of the curvature vectors of the at least one ridge in the plurality of points of the at least one ridge. i* ia. A method for according to claim wherein the plurality of points of the at least one ridge is positioned on the same ridge. method for according to claim or wherein the plurality of points of the at least one ridge is positioned in a sub-area of the sample.
SE1950074A 2019-01-23 2019-01-23 A method for comparing a sample comprising fingerprint information with a template SE543667C2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
SE1950074A SE543667C2 (en) 2019-01-23 2019-01-23 A method for comparing a sample comprising fingerprint information with a template

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1950074A SE543667C2 (en) 2019-01-23 2019-01-23 A method for comparing a sample comprising fingerprint information with a template

Publications (2)

Publication Number Publication Date
SE1950074A1 SE1950074A1 (en) 2020-07-24
SE543667C2 true SE543667C2 (en) 2021-05-25

Family

ID=72140795

Family Applications (1)

Application Number Title Priority Date Filing Date
SE1950074A SE543667C2 (en) 2019-01-23 2019-01-23 A method for comparing a sample comprising fingerprint information with a template

Country Status (1)

Country Link
SE (1) SE543667C2 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5717786A (en) * 1994-06-21 1998-02-10 Nec Corporation Apparatus for determining ridge direction patterns
EP1197912A2 (en) * 2000-10-11 2002-04-17 Hiroaki Kunieda System for fingerprint authentication
EP1498837A1 (en) * 2003-07-15 2005-01-19 Identification Systems DERMALOG GmbH Method of extracting minutiae characteristics for automatic fingerprint identification
US20080013803A1 (en) * 2006-07-13 2008-01-17 Motorola, Inc. Method and apparatus for determining print image quality
WO2016135704A1 (en) * 2015-02-27 2016-09-01 Idex Asa Curve matching and prequalification

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5717786A (en) * 1994-06-21 1998-02-10 Nec Corporation Apparatus for determining ridge direction patterns
EP1197912A2 (en) * 2000-10-11 2002-04-17 Hiroaki Kunieda System for fingerprint authentication
EP1498837A1 (en) * 2003-07-15 2005-01-19 Identification Systems DERMALOG GmbH Method of extracting minutiae characteristics for automatic fingerprint identification
US20080013803A1 (en) * 2006-07-13 2008-01-17 Motorola, Inc. Method and apparatus for determining print image quality
WO2016135704A1 (en) * 2015-02-27 2016-09-01 Idex Asa Curve matching and prequalification

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Lei J., You X., Zhou L., Zeng, W. "Extracting corner-cue feature to improve minutiae-matching accuracy" In: 2010 17th IEEE International Conference on Image Processing (ICIP 2010), 2010, September, ISBN: 978-1-4244-7992-4 *
Zacharias G. C, Nair M. S., Lal P. S., "Fingerprint reference point identification based on chain encoded discrete curvature and bending energy", In: Pattern Analysis and Applications, 2016, June, vol. 20, nr. 1, ISSN 1433-7541 *

Also Published As

Publication number Publication date
SE1950074A1 (en) 2020-07-24

Similar Documents

Publication Publication Date Title
JP6444523B2 (en) Fingerprint recognition method and fingerprint recognition apparatus
US10740589B2 (en) Skin information processing method, skin information processing device, and non-transitory computer-readable medium
CN106203305B (en) Face living body detection method and device
EP2833294B1 (en) Device to extract biometric feature vector, method to extract biometric feature vector and program to extract biometric feature vector
US9613428B2 (en) Fingerprint authentication using stitch and cut
US8989455B2 (en) Enhanced face detection using depth information
Labati et al. Contactless fingerprint recognition: a neural approach for perspective and rotation effects reduction
CN101777128B (en) Fingerprint minutiae matching method syncretized to global information and system thereof
US20190163954A1 (en) Fingerprint enrollment method and apparatus
JP2012519927A (en) A novel inpainting technique and method for reconstructing iris scans through partial acquisition mosaic processing
US10869617B2 (en) Gait pathology detection and monitoring system, and method
SG181597A1 (en) Head recognition method
CN105550630B (en) A kind of fingerprint authentication method and device
Darwaish et al. Biometric identification on android smartphones
US20180005394A1 (en) Systems and methods for point-based image alignment
US10740590B2 (en) Skin information processing method, skin information processing device, and non-transitory computer-readable medium
TW201624352A (en) Optical fingerprint recognition apparatus
WO2019228471A1 (en) Fingerprint recognition method and device, and computer-readable storage medium
US20160063295A1 (en) Fingerprint detection sensor and fingerprint detection system comprising the same
SE543667C2 (en) A method for comparing a sample comprising fingerprint information with a template
JP6526494B2 (en) INFORMATION PROCESSING PROGRAM AND INFORMATION PROCESSING DEVICE
KR101995025B1 (en) Method and Apparatus for Restoring Fingerprint Image Using Fingerprints Left on Fingerprint Sensor and Touch Screen
KR101548625B1 (en) Method for removing glint and control device for recognizing iris using the same
Verlekar et al. Walking direction identification using perceptual hashing
CN110659536A (en) Method, device and system for testing resolution of fingerprint identification equipment and storage medium