Basictypes
Therearethreebasicshapesoffingerprintlines-whorl,archandloop.Itisthesubcutaneoustissueoppositetothetopofthefingerbelly.Thedifferentpressingdirectioncreatesthisdifferentshape.Studieshaveshownthatifsomeone’sfingeristallandround,thepatternoftheirfingerprintswillbespiral.Scientistshavebeenabletoreproducethemorecommonfingerprintsthroughthemodel,andcanalsorepeattheformationprocessofthelesscomplicatedrarefingerprints.
Fingerprintstructure
Fingerprints,alsocalledhandprints,havebroadandnarrowmeanings:fingerprintsinanarrowsenserefertothepatternofmastoidlinesonthepalmsurfaceofthefirstsectionofahumanfinger;Inabroadsense,fingerprintsincludefingerprints,knuckleprintsandpalmprints.Thereisaliteraldifferencebetweenfingerprintsandfingerprints,thatis,fingerprintsrefertothepapillarylinepatternonthepalmsurfaceofthefirstfinger,andfingerprintsarethemarksleftbythispapillarylinepattern.However,injudicialpractice,itiscustomarythatfingerprintsandTheconceptoffingerprintsisuniversal.
Theimprintsaremainlyduetothepresenceofalargenumberofsweatglandsandsebaceousglandsontheskinofhumanfingersandpalms(thinkofthesweatinyourpalmswhenyouarenervousorexcited).Aslongaslifeactivitiesexist,Sweatandsebumarecontinuouslydischarged.It'sabitlikeanatomicsealthathasinkconstantlypermeatingthesurfaceoftheprintedtext.Therefore,aslongasthefingerorpalmtouchesthesurfaceoftheobject,itwillautomaticallyleaveamarklikeanatomicseal.Ofcourse,thisismainlythereasonwhythefingersandpalmsthemselvescanleavefingerprints.Ifthefingersandpalmsarestuckwithotherliquid-likesubstances,suchasoilsontheheadandface(thisisthe"inkpad"youusemostoften),blood,andinktoholdfingerprints,theprincipleofleavingfingerprintsismorelikeanormallid.seal.
Zjišťování otisků prstů, včetně vyhledávání a objevování otisků prstů. Rozsah vyhledávání otisků prstů:(1)centrum kriminální činnosti;(2)portál a export místa a jeho okolí;(3)položky, kterých se zločinci mohli dotknout;(4)různý objekt.
Andtheircomplexityissufficienttoprovideenoughfeaturesforidentification.Inadditiontobeingunique,fingerprintsarealsohereditaryandimmutable.Ithasnotbeenfoundthatdifferentpeoplehavethesamefingerprints,soeachperson'sfingerprintsarealsodifferent.Becausefingerprintsareuniquetoeveryone,fingerprintsleftbycriminalsatthesceneofcrimeshavebecomeimportantcluesforthepolicetopursuesuspectsinthepastfewhundredyears.Nowadays,fingerprintidentificationmethodshavebeencomputerized,makingtheidentificationprocessfasterandmoreaccurate.
Becauseeveryonehasdifferentgeneticgenes,fingerprintsarealsodifferent.However,althoughtheformationoffingerprintsismainlyaffectedbygenetics,therearealsoenvironmentalfactors(5%).Whenthefetusdevelopsinthemother'sbodyforthreetofourmonths,thefingerprintsarealreadyformed,andthefingerprintsofchildrenwillslightlychangeduringthegrowthperioduntiladolescence.Theshapeisonlysetataround14yearsold.Intheprocessofskindevelopment,althoughtheepidermis,dermis,andstromallayersallgrowtogether,thesoftsubcutaneoustissuegrowsfasterthantherelativelyhardepidermis.Somepeoplesaythatfingerprintswillchangeafterbonemarrowtransplantation,whichiswrong.Unlessitisskingraftingordamagethatreachesthebasallayer,fingerprintswillnotchange.
Formthefoundation
Duringthedevelopmentoftheskin,althoughtheepidermis,dermis,andstromallayersareallgrowingtogether,thesoftsubcutaneoustissuegrowsfasterthanthehardepidermis,soitwillTheepidermisproducesasteadystreamoftoppressure,whichforcestheslower-growingepidermistoshrinkandcollapsetowardtheinnerlayeroftissues,graduallybendandwrinkle,soastoreducethepressureexertedbythesubcutaneoustissuesonit.Inthisway,ontheonehand,itisforcedtoattackupwards,andontheotherhand,itisforcedtowithdraw,causingtheskintogrowtortuously,pitsanduneven,forminglines.Thisprocessofbendingandwrinklingfluctuateswithchangesintheupperpressuregeneratedbytheinnertissue,formingunevenridgesorfolds,untilthedevelopmentprocessisstopped,andfinallyshapedintoafingerprintthatwillnotchangetodeath.
Genetické problémy
Dědí se otisky prstů?
Althoughtherearenotwoidenticalfingerprintsintheworld,thefingerprintsofidenticaltwinsarerelativelysimilar.Moreover,thepatternsofdifferentfingersofthesamepersonalsohavesimilarities.Thestudyfoundthattherearegenderdifferencesandethnicdifferencesinfingerprinttypeswithhighoccurrencerates.Forexample,inthefingerprintsofChineseandJapanese,theoccurrencerateofbucketpatternandskippatternisroughlythesame,accountingformorethan90%ofthetotal;inthefingerprintsofEuropeans,theoccurrencerateofskippatternishigher;inthefingerprintsofAmericans,Theappearancerateofbowpatternishigher.
Becausethefingerprintsofidenticaltwinsorthesameracearesimilar,itcanalsobesaidthatfingerprintscanbe"inherited".However,theformationoffingerprintsisnotonlyaffectedbygeneticgenes,butalsobyenvironmentalfactors.ProfessorKazuInoueofHokkaidoUniversityinJapanhasbeenengagedinanatomicalresearchforalongtime.Hesaid:"Thedetailsofhumanbodyalsovaryfrompersontoperson.Becausefingerprintsareveryconvenienttouse,theyarewidelyusedtoidentifyidentity."
Jak se tvoří otisky prstů?
Whenthefetusdevelopsto4months,ithasalreadyformedafingerprint.Beforethat,about10weeksofdevelopment,fingertipsandotherpartswilltemporarilyformalargeball-shapedbulge—justlikethepadofacat'spaw,whichplaysadecisiveroleintheformationoffingerprints.
Whenthebulgebeginstoshrinkandcollapse,wrinklesbegintoappearatthejunctionoftheepidermisandthedermis.Thisisthebudding"fingerprintmold".Thecellsgeneratedbythefingerprintmoldsqueezehardtothesurface,andwhenthefetusdevelopsto4months,itwillformfingerprintsontheepidermis.Researchsuggeststhatfingerprintsaredevelopedfromdenselyarranged"molds"onthebulgesurface.Therefore,theshapeandsizeoftheoriginalbulgedeterminestheshapeofthefingerprint.
Usesoffingerprints
Asweallknow,fingerprintshavethecharacteristicsof"differentandunchangingforlife".Longago,peopleusedhandprintsonpaperorwoodenboardstoidentifytheiridentity.Fingerprintshavebeenwidelyusedinareassuchasentryinspectionsandcriminalsearches.Fingerprintsarelinesformedbylinearlyarrangedprotrusionsanddepressionsontheepidermis,"akindofskinpattern".Humanhandsandfeetarecoveredwithskinlinesontheinside.Fingerprintsarewidelyusedinareassuchassearchingforcriminalstoidentifyidentities.Asweallknow,theBabyloniansandChinausedfingerprintstoverifytheidentityofapersonalongtimeago.
Usingfingerprintstoidentifyidentity,thisisbecausefingerprintsmeetthefollowingtwoconditions:
Firstofall,fingerprintsarenotthesame,andtherearenotwoidenticalfingerprints.Althoughidenticaltwinshaveahighdegreeofsimilarityintheirpatterns,theirdetailedfeaturesarenotexactlythesame,buttherearecertaindifferences(seeFigure1forfeaturepoints).Inaddition,thefingerprintsofdifferentfingersofapersonarealsodifferent.
Secondly,aperson’sfingerprintisinprinciplethesameforlife.Whenachildgrowsup,thefingerprintisonlyenlargedandthickened,anditspattern,numberoflinesandothercharacteristicsremainunchanged.
Figure2showsthethreetypesoffingerprints(skippattern,bucketpattern,bowpattern),andshowsasubcategoryofbucketpatternandbowpattern.Thepictureontherightshowstheinternalstructureoftheskin.Althoughthereareothertactileorgans,onlythepartsinvolvedinthetextareshownhere.
Thedermisislocatedinthelowerlayeroftheepidermis,andthejunctionbetweentheepidermisandthedermisisunevenandintricate.Theseconcavitiesandconvexitiesare"molds"andfinallyformfingerprintpatterns.Eveniftheepidermisiswornoff,aslongastheinnerdermislayerisnotdamaged,thesamefingerprintscanstillgrowaftertheinjury.Theclarityoffingerprintswillgraduallyblurwithage.In1880,Fulders,aBritishmissionaryanddoctorlivinginJapan,publishedthefirststudyonfingerprintsintheBritishacademicjournal"Nature",expoundingforthefirsttimethatfingerprintrecognitionisusedincriminalinvestigationandotherfields.Theapplicationof,createdaprecedentformodernfingerprintresearch,whichwasintroducedtoAsiain1900andwasputintopractice.
Peoplehavealwaysbelievedthatfingerprintscannotonlyhelppolicesolvecrimes,butalsoenhanceskinfriction.However,afterscientistsmeasuredtheinfluenceoffingerprintsonfriction,theycameupwithdifferentresults.
Thescientistsfirstaskedthevolunteerstopresstheirfingersontheglasstocalculatetheaveragefrictioncausedbythefingerprintsatthistime;then,theyaskedthevolunteerstograduallyincreasethepressureonthefingersandperformcalculations.Itturnedoutthatthefrictiondidnotincreaseasexpected.Furthermicroscopicexaminationrevealedthatthefingerprintslookedlikegulliesunderthemicroscope,withgapsbetweenthem.Comparedwithaperfectlysmoothfingersurface,thecontactareawasreducedbyabout1/3.Thisisabitsimilartorubber,andthefrictionvarieswiththecontactarea.Basedonthis,scientistsbelievethatfingerprintsactuallyreducefriction,makingtheskineasiertostretchanddeform,sothatitcanavoidskindamage.
Metoda pozorování
Podle různých tradičních metod lze otisky prstů rozdělit do tří kategorií:
První kategorie je otisk jater, který je cílovým otiskem. Čáry lze vidět pohledem. Například ručně namáčená barva, krev, inkoust a další položky se přenášejí, obvykle se tisknou na kartu otisku prstu ze základních dat;
Thesecondtypeisplasticprint,whichreferstothesoftSubstances,suchasfingerprintsimprintedoncandlesandclaybyhandcontact;
Thethirdtypeislatentprint,whichisafingerprintthatistransferredbythebody’snaturalsecretionssuchassweat.Thelinesarenoteasytofindvisually,andarethemostcommonfingerprintsinthecrimescene.Latentfingerprintsareoftenleftafterthefingersfirsttouchgrease,sweatordust,andthentouchacleansurface.Althoughthesefingerprintscannotbeseenwiththenakedeye,theycanbeprocessedbyspecialmethodsandusingsomespecialchemicalreagents.Revealtheselatentfingerprints.
Fyzikální metoda
Na povrchu nesavých materiálů, jako jsou kovy, plasty, sklo, dlaždice atd., se mohou obvykle používat otisky prstů. Objeví se otisky prstů.
(1)Prášková metoda, vyberte prášek s velkým barevným kontrastem a posypte jej, abyste extrahovali kompletní otisky prstů;
(2)Metoda magnetického prášku, použijte jemné železné práškové částice s magnety, jako štětec, přejeďte zpět a dopředu, abyste odhalili otisky prstů.
(3)Lasermethod.Withthedevelopmentoflasertechnology,ourcountryuseslasertodisplayfingerprints.Thedisplaydeviceusesanargonionlaser.Laserscandisplayfingerprintsbecausethereisalwaysalayerofsweatandfattyacidsonthesurfaceofhumanfingers,whichleavesinconspicuousfingerprintsaftertouchingobjects;withlaserlight,sweat,fattyacids,etc.willproducecolorfluorescence,andthefingerprintswillbeclear..Useadedicatedfingerprintcameratotakeclearfingerprintphotos.Afterthephotoisenlarged,itbringsalotofconveniencetotheappraisalwork.
Chemická metoda
Pokud se na povrchu savého povrchu bez papíru, karet, kůže, dřeva atd. uvolní otisky, musí být chemicky ošetřeny, než je lze odhalit v laboratoři.
Iodinefumigationmethod-theuseofiodinecrystalstoheattogeneratesteam,afteritreactswiththegreaseofthefingerprintresidue,yellow-brownfingerprintswillappear,whichmustbetakenimmediatelyorfixedbychemicalmethods;
Ninhydrinmethod-spraythereagentonthespecimen,andafterreactingwiththeaminoacidsinbodysecretions,itwillshowapurplefingerprint;
Silvernitratemethod-nitricacidAfterthesilversolutionreactswiththesodiumchlorideintheresidualsweat,itwillproduceblackfingerprintsinthesun;
Fluorescencereagentmethod—fluoresceinando-phthalaldehydequicklyinteractwiththeproteinorfingerprintresiduesTheactionofaminoacidsproduceshighlyfluorescentfingerprints.Thisreagentcanbeusedonthesurfaceofcoloredobjects.
Three-secondgluemethod-thecyanoacrylateisvaporized,andtheresidualsubstancesonthefingerprint,suchasaminoacidsandglucose,willreactwiththevaporizedglueandmakethefingerprintappear.
(1)Metoda pozorování dechu: Pozorujte dýchání na povrchu hladkého objektu;
(2)Visualobservationmethod:Observewithacertainlightandangle.Withthehelpofbacklighting,fingerprintscanoftenbedisplayed.Thisisbecausefingerprintsareoftenstainedwithdust,whichabsorbslightandappearsdark.
(3)Metoda pozorování pomocí lupy:pozorujtepodurčitésvětloaúhel pomocí lupy;
(4)Metoda ultrafialového pozorování: pozorujte s charakteristikami ultrafialového záření;
(5)Physicalandchemicalobservationmethod:Forpotentialfingerprintsthataredifficulttoobservewiththenakedeye,physicalandchemicaltreatmentsareneededtofindout.
(6)Cyanidegluemethod:firstprepareasolutionofcyanideglueandether,immersethefilterpaperofasuitablesizeinthesolution,takeitoutanddry,andcontactthefilterpaperwiththefingerprintfor5-60minutes.Thepartofthefingerprintclosetothepapervolatilizesduetotheeffectoftheglue,andthepatternappearsonthesurfaceofthefilterpaper.
Specialfingerprints
Peoplewithspecialdiseasesleave"specialfingerprints"atthescene,whicharemainlyseenincertaindiseasesthatcanchangethepatient'ssweat.Likediabetes,becausethesugarcontentinthesweatofthepatientincreases,ifalotofsweatleavesfingerprints,theremaybeaphenomenonofantsandbeesgatheredinsomenovelsorpuzzles.Also,asmentionedonTVsometimeago,somepeopleusedinferiorporcelainteacupstodrinkteaforalongtime,resultingincopperpoisoning,whichresultedinredsweats.Forpatientslikethis,iftheyleavefingerprints,theywillfindthatthefingerprintsarered.
InArgentina,usingfingerprintevidencetomakeawomanwhokilledhertwochildrenconfessedtoacrime,thisisthefirsttimethatmodernfingerprintinspectiontechnologyhasbeenadoptedbyacourt.
Withthedevelopmentofscienceandtechnology,fingerprintshavenewusesinmedicine.Somedoctorshavediscoveredthatcertaindiseasescanbedetectedbycheckingaperson'sfingerprintsandpalmprints.
Fingerprintshavebecomegoodfriendswithelectroniccomputers.
Manybusinessesalsousethecharacteristicsoffingerprintstodevelopsomehigh-techequipmenttoreflecttheconvenienceandsafetythatfingerprintsbringtolife,suchasfingerprintlocks,fingerprintaccesscontrol,fingerprintattendancemachines,fingerprintcollectionDevice,fingerprintsafe,networkfingerprintlogintechnologyandsoon.Accordingtothesurvey,manyhigh-endsmartcommunitiesinChinaareequippedwithfingerprintlocksandfingerprintaccesscontrol.Theearliestfingerprintsusedintheequipmentisthefingerprintattendancemachine.Inordertopreventthegenerationofcards,thecompany'spersonnelmanagershaveadoptedfingerprintattendancemachinesoneafteranother.Atthesametime,mycountry'sfirstnetworkfingerprintlogintechnologyproviderhaslaunchedabetaversion,whichisexpectedtosolvetheproblemofnetworkaccountsecurity.
Whatnewuseswillsmallfingerprintshaveinthefuture?Anewmazeisbeforeusagain,waitingforustoexploreandseek.
Animalfingerprints
Thestudyfoundthatinadditiontohumans,primatessuchasgorillas,chimpanzees,orangutansalsohaveskinpatternsonthehandsandfeet,andeventhearborealkoalaSkinpatternsarealsofoundonanimalsofitskind(Possumidae).Inaddition,spidermonkeysandcapuchinmonkeyslivinginSouthAmericahaveacurlytail,whichcandexterouslygraspobjects,andtheyalsohaveskinpatternsontheinsideoftheirtails.Itcanbeinferredfromthisthatitisalwayseasiertoformskinlinesontheskinwhereananimalisgrabbinganobject.
Principyrozpoznávání
Rozpoznávání otisků prstů
Readfingerprintimages,extractfeatures,savedataandcompare.Atthebeginning,theimageofthehumanfingerprintisreadbythefingerprintreadingdevice.Afterthefingerprintimageisobtained,theoriginalimagemustbepreliminarilyprocessedtomakeitclearer.Next,thefingerprintrecognitionsoftwareestablishesthedigitalrepresentationofthefingerprint-characteristicdata,aunidirectionalconversionthatcanconvertfromfingerprinttocharacteristicdatabutnotfromcharacteristicdatatofingerprint,andtwodifferentfingerprintswillnotproducethesameCharacteristicdata.
Somealgorithmscombinethenodeanddirectioninformationtogeneratemoredata,whichindicatestherelationshipbetweeneachnode,andsomealgorithmsalsoprocesstheentirefingerprintimage.Inshort,thesedata,usuallycalledtemplates,aresavedas1Krecords.Nomatterhowtheyarecomposed,thereisstillnostandardfortemplatesandnopublishedabstractalgorithms.Instead,eachmanufacturerdoesitsownthing.Finally,throughthemethodofcomputerfuzzycomparison,thetemplatesofthetwofingerprintsarecompared,andthedegreeofsimilaritybetweenthemiscalculated,andfinallythematchingresultofthetwofingerprintsisobtained.Fingerprintsareactuallymorecomplicated.
Unlikemanualprocessing,manybiometrictechnologycompaniesdonotdirectlystorefingerprintimages.Overtheyears,manydigitalalgorithmshavebeenproducedinvariouscompaniesandtheirresearchinstitutions(therelevantlawsoftheUnitedStatesbelievethatfingerprintimagesarepersonalprivacy,sofingerprintimagescannotbestoreddirectly).
Fingerprintrecognitionalgorithmsultimatelyboildowntofindingandcomparingfingerprintfeaturesonfingerprintimages.ThecharacteristicsoffingerprintsWedefinetwotypesofcharacteristicsoffingerprintstoverifyfingerprints:overallcharacteristicsandlocalcharacteristics.Generalfeaturesrefertothosefeaturesthatcanbedirectlyobservedbythehumaneye,including:basicpatternpatterns,loop,arch,andwhorl.Otherfingerprintpatternsarebasedonthesethreebasicpatterns.Relyingonthepatterntypetodistinguishfingerprintsisfarfromenough.Thisisonlyaroughclassification,butclassificationmakesitmoreconvenienttosearchforfingerprintsinlargedatabases.
Oblast vzoru
(PatternArea)Thepatternareareferstotheareaonthefingerprintthatincludestheoverallcharacteristics,thatis,itcanbedistinguishedfromthepatternareathatthefingerprintbelongstoWhichtype.Somefingerprintrecognitionalgorithmsonlyusethedatainthepatternarea.Aetex'sfingerprintrecognitionalgorithmusestheobtainedcompletefingerprintinsteadofjustthepatternareaforanalysisandrecognition.
CorePoint(CorePoint)Základní bod je umístěn v progresivním středu vzoru otisku prstu. Používá se jako referenční bod pro čtení otisků prstů a porovnávání otisků prstů.
Triangularpoint(Delta)Thetriangularpointislocatedatthefirstbifurcationorbreakpointfromthecorepoint,orwherethetwostripedroadsconverge,isolatedpoints,orturningpoints,Orpointtothesesingularities.Thetriangularpointprovidesthestartingpointforcountingandtrackingfingerprintlines.
TypeLines(TypeLines)Thetypelinesarecrosslinesthatappearwherethelinessurroundingthepatternareabegintobeparallel.Thestylelinesareusuallyshortandinterrupted,butItsouterlinebegantoextendcontinuously.
Numberoffingerprints
(RidgeCount)referstothenumberoffingerprintsinthepatternarea.Whencalculatingthenumberoffingerprints,usuallyconnectthecorepointandthetrianglepointfirst,andthenumberofintersectionsofthislinewiththefingerprintlinecanberegardedasthenumberoffingerprints.LocalfeaturesLocalfeaturesrefertonodesonthefingerprint.Twofingerprintsoftenhavethesameoverallcharacteristics,buttheirlocalfeatures-nodes,cannotbeexactlythesame.Nodes(MinutiaPoints)Fingerprintlinesarenotcontinuous,smoothandstraight,butofteninterrupted,bifurcatedorDiscount.Thesebreakpoints,bifurcationpoints,andturningpointsarecalled"nodes."Itisthesenodesthatprovidefingerprintconfirmationnodecharacteristics
1. Klasifikace – Existuje několik typů uzlů, z nichž nejtypičtější jsou koncové body a body rozvětvení
A.Koncové body(Konec)-astripedroadendshere.
B. Bifurkace-pruhová cesta je zde rozdělena do dvou nebo více čar.
C.RidgeDivergence-Dvouparalelnost zde oddělená.
D.DotorIsland(DotorIsland)-zejména krátká linka,takže se stane bodem.
E.Uzavření-cesta za pruhemje rozdělena do dvou,okamžitě se sloučí do jedné a malý kroužek vytvořený v této cestě se nazývá centrovací bod.
F.ShortRidge(ShortRidge)-vzor, který je krátký, ale nestává se bodem.
2.Orientace-thenodecanfaceurčitýsměr.
3.Zakřivení ---popište rychlost, kterou se mění směr zrn.
4.Pozice(Pozice)-polohauzlujepopsána(x,y)souřadnicemi,které mohou být absolutní,neborelativní k trojúhelníkovému bodunebokonstrukčnímu bodu.
Jak získat
Za prvé, technologie optického rozpoznávání
Theuseofopticaltechnologytocollectfingerprintsistheoldestandmostwidelyusedtechnology.Putyourfingerontheopticallens,andusetheprismtoprojectthefingeronthechargecoupleddevice(CCD)undertheilluminationofthebuilt-inlightsource,andthenformtheridges(thelineswithacertainwidthanddirectioninthefingerprintimage),whichareblackandvalleys.Theline(theconcavepartbetweenthelines)isawhitedigitizedmulti-grayfingerprintimagethatcanbeprocessedbythefingerprintdevicealgorithm.
ZadruhéTechnologie rozpoznávání teplotních senzorů
Itsadvantageisthatfingerprintimagescanbeacquiredwithin0.1s,andthesensorhasthesmallestvolumeandarea,whichisusuallyTheso-calledslidingfingerprintreaderadoptsthistechnology.Thedisadvantageis:subjecttotemperaturelimitations,afteralongtime,thefingerandthechipareatthesametemperature.
3.Polovodičové křemíkové snímací technologie (kapacitní technologie)
SemiconductorcapacitancesensorisbasedonthecapacitancevalueformedbytheridgeandridgeofthefingerprintandthesemiconductorcapacitancesensingparticlesThesizeisdifferenttodeterminewhichpositionisthecrestandwhichpositionistheyu.Itsworkingprocessistopre-chargethecapacitivesensingparticlesoneachpixeltoacertainreferencevoltage.Whenthefingertouchesthefingerprintperformanceofthesemiconductorcapacitor,becausetheridgeisconvexandtheridgeisconcave,accordingtotherelationshipbetweenthecapacitancevalueandthedistance,differentcapacitancevalueswillbeformedattheridgeandtheridge.Thenusethedischargecurrenttodischarge.Becausetheridgeandyuhavedifferentcapacitancevalues,theirdischargespeedsarealsodifferent.Thepixelsunderthecrest(highcapacitance)dischargemoreslowly,whilethepixelsundertheridge(lowcapacitance)dischargefaster.Dependingonthedischargerate,thepositionsoftheridgesandridgescanbedetectedtoformfingerprintimagedata.
Čtyři.Ultrazvuková technologie
Ultrazvuková frekvence používaná ultrazvukovou technologií je 1×104Hz-1×109Hz, energie je řízena do té míry, aby nepoškodila lidské tělo (stejná intenzita jako její bezlékařská diagnostika, může vyžadovat všechny produkty ultrazvukové techniky. ale doba jeho odběru bude výrazně delší než u výše uvedených dvou typů výrobků a je drahá a nelze ji použít k identifikaci otisku živého prstu.
Importantconcepts
AsanewITtechnologyfield,fingerprintrecognitiontechnologyhasmanynewconcepts.Understandingtheconceptoffingerprintidentificationtechnologyhelpstounderstandfingerprintidentificationtechnologyaccurately.
Identificationsystem
Afterthedevelopmentofthefingerprintidentificationsystemfrommanualidentificationtomachineidentification,itenterstheautomaticidentificationstage,whichiscalledtheautomaticfingerprintidentificationsystem(AFIS).Atypicalautomaticfingerprintidentificationsystemincludesafront-endsubsystemthatinteractswithpeople-automaticfingerprintacquisitionequipment,aback-endsubsystemthatcompletesfingerprintimageprocessingandfeaturevalueextraction,andadatabasesubsystemforfingerprintlibrarystorage.Whenthebackgroundsubsystemisusedinthefingerprintregistrationprocess,itcanbecalledthefingerprintregistrationsubsystem.Whenitisusedinthefingerprintidentificationprocess,itiscalledthefingerprintidentificationsubsystem.
Registrationmatching
Fingerprintregistrationisalsocalledfingerprintregistration.Thisistheprocessofextractingfingerprintfeaturevaluesfromthefingerprintimage,formingafingerprintfeaturevaluetemplate,combiningitwiththeperson'sidentityinformation,andstoringitinthefingerprintidentificationsystem.Itisequivalenttoreportinganaccountforfingerprints.Therefore,whenregisteringfingerprints,itisnecessarytoensurethecorrectcorrespondencebetweenfingerprintsandidentityinformation.Inparticular,itisveryimportanttopreventimpostersandavoiderrorsintheassociationoffingerprintsandidentityinformationwhenthegovernment,associations,companiesandotherunitsperformfingerprintregistration.Therefore,inthistypeoffingerprintapplication,theprocessoffingerprintregistrationrequirestheparticipationofon-sitesupervisors.Itevencollectsthesupervisor’sfingerprintsintothesystemasacomponentoftheregistrant’sfingerprintfeaturevaluetemplatetoshowtheimportanceofresponsibilitiesandprovideabasisforfollow-upresponsibilityaudits.
Identificationandverification
Identificationandverificationisnotaprobleminthefieldoffingerprintrecognitionalgorithms,butaprobleminthefingerprintrecognitionsystem.Fingerprintrecognitionreferstomatchingfingerprintfeaturevaluesin1:Nmode.Itistheprocessofidentifyingaspecificfingerprintfrommultiplefingerprinttemplates.Theresultis"Yes"or"No."Sometimesinformationabout"whois"isgiven.
Fingerprintverificationreferstomatchingfingerprintfeaturevaluesin1:1mode.Itisaprocessofmatchingthefingerprintfeaturetemplatetobecomparedwithanotherfingerprintfeaturetemplatethatexistsinadvance.Theresultis"isitright".Either1:1modeor1:Nmodecanbeusedinasystem,whichdependsonthecharacteristicsandrequirementsoftheapplicationsystem.Sometimesyoucanalsoconvertthe1:Nmodetothe1:1modetoimprovethesystemsecurityandcomparisonspeedasrequiredbythebusinessmodel.
Výhody:
1.Otisky prstů jsou různé vlastnosti lidského těla a jejich složitost je dostatečná k tomu, aby poskytovala dostatečné vlastnosti pro identifikaci.
2.Pokud chcete zvýšit spolehlivost, musíte pouze zaregistrovat více otisků prstů a identifikovat více prstů, až deset, a každý otisk prstu není stejný.
3.Skenování otisků prstů je velmi pohodlné.
4.Při čtení otisku prstu se uživatel musí dotknout prstu a hlavy pro pořízení otisků prstů přímo.
5.Kontaktujte nejspolehlivější způsob čtení lidských biologických charakteristik.
6.Hlava pro snímání otisků prstů může být více miniaturizována a cena bude nižší.
Nevýhody:
1.Někteří lidé nebo určité skupiny mají několik funkcí otisků prstů a jsou velmi obtížné.
2.V minulosti způsobovalo použití otisků v trestních záznamech některé lidi, kteří se báli "zaznamenávání otisků prstů."
3.Infact,thefingerprintidentificationtechnologycannotstoreanydatacontainingthefingerprintimage,butonlystoretheencryptedfingerprintcharacteristicdataobtainedfromthefingerprint.
4.Při každém použití otisku prstu se otisk prstu uloží na snímací hlavu otisku prstu a tyto stopy otisků prstů lze použít ke kopírování otisků prstů.
FRRandFAR
FRR(FalseRejectionRate)andFAR(FalseAcceptanceRate)arethetwomainparametersusedtoevaluatetheperformanceoffingerprintrecognitionalgorithms.FRRandFARaresometimesusedtoevaluatetheperformanceofafingerprintrecognitionsystem,butthisisnotappropriate.Inadditiontotheperformanceofthefingerprintidentificationsystembeingaffectedbythefingerprintalgorithm,theimpactoftheperformanceofthefingerprintcollectiondeviceonFRRandFARcannotbeignored.
FRRiscommonlycalledfalserejectionrate,andthestandardnameisFNMR(FalseNon-MatchRate,mismatchrate).Itcanbeeasilyunderstoodastheprobabilityof"takingfingerprintsthatshouldbesuccessfullymatchedwitheachotherasfingerprintsthatcannotbematched".Theperformancemeasurementofthefingerprintalgorithmismeasuredundertheconditionofagivenfingerprintlibrary.ThefingerprintlibraryusedformeasurementisgenerallygivenbytheorganizerofFVC(InternationalFingerprintIdentificationAlgorithmCompetition).WhenFVCperformsthefingerprintrecognitionalgorithmperformancetest,thereisnoexternalfingerprintinput,anditusesastandardfingerprintimagelibrarytotest.Therefore,FNMRisatestvalueobtainedwithoutconnectingafingerprintcollectiondevice.Theotherparametersinthissectionarealsoderivedunderthispremise.
Za předpokladu, že v knihovně otisků prstů je 100 prstů s různými ID a každý prst je registrován pomocí 3 otisků prstů, v knihovně otisků prstů je celkem 300 otisků prstů. Za předpokladu, že P1představuje dílčí otisk<>1. , P1- F2,P1-F3.FNMR odkazuje na porovnávání 3 otisků stejného prstu v páru databáze otisků prstů, jmenovitě P1-F1aP1-F2se shoduje,P1-F1aP1 -F3Shoda,P1-F2shodaP1-F3 ,P1-F2odpovídáP1-F1,P1- F3matchesP1-F1,P1-F3matchesP1-F2 ,Existuje 6 metod porovnávání. Vytvořte 6 druhů shod pro všech 100 prstů uvnitř, celkem 6 × 100 = 600 shod. Teoreticky lze správně porovnat 600 shod a úspěšnost shody je 100 %. Ve skutečnosti, protože zkušební obraz otisku tří prstů nemůže být součet.Předpokládejme, že nastavíme podobnost úspěšného spárování na > 90 %, to znamená, že když je podobnost větší než 90 %, znamená to, že shoda je úspěšná. Pak zjistíme, kolikrát je podobností než 90 % z těchto 600 shod. 70.Z toho 600krát označte početkrát, kdy došlo k neúspěšnému zápasu, což je 600-570= 30krát. Neúspěšnost shody je 30/600=5 %.
Forthefingerprintrecognitionalgorithm,whenthefingerprintdatabaseisconfirmed,thematchingfailurerateFNMRiscertain.Whenthefingerprintlibrarychanges,itsFNMRwillalsochange.Therefore,internationally,thefingerprintlibrarypublishedbyFVCisusedasaunifiedtestlibrary,andtheFNMRresultstestedinthetestlibraryareusedasastandardreferenceformeasuringtheperformanceoffingerprintalgorithms.
FARisgenerallycalledthefalserecognitionrate,anditsstandardnameisFMR(FalseMatchRate).FMRisthemostimportantparameterusedtoevaluatetheperformanceoffingerprintrecognitionalgorithms.Itcanbeeasilyunderstoodastheprobabilityof"takingfingerprintsthatshouldnotbematchedasmatchedfingerprints".
Alsotakethefingerprintlibraryinthepreviousparagraphasanexample.Matcheachfingerprintinthelibrarywithallotherfingerprintsexceptyourself.Thetotalnumberofmatchesis300×(300-1)=89700times.Intheory,thenumberofsuccessfulmatchesis6×100=600times,andthenumberoffailedmatchesshouldbe89700-600=89100times.Supposethatduetotheperformanceofthefingerprintalgorithm,thematchthatshouldhavefailedisjudgedasasuccessfulmatch,ifitisassumedthatthenumberofsucherrorsis100times.ThefalseacceptancerateFARis100/89100=0.11%.Thenumberofmatchingfailuresvariesduetothestrictnessofthesimilarconditions.Whenthefilterconditionthatmatchessuccessfully,thatis,thethresholdvalueincreases,theFARwilldecrease.
FARisalsorelatedtofingerprintlibrary.IntheFVCcompetition,thereare4fingerprintlibrariesfortesting,andtheaverageistaken.Oneofthefingerprintlibrariesisartificiallygeneratedtoeliminatetheeffectofdifferentfingerprintimagequalitycausedbydifferentcollectiondevicesontheperformanceofthealgorithm.
Inthesamefingerprintlibrary,forthesamealgorithm,athresholdneedstobesetasacriterionforjudgingsimilarity.Whenthesimilarityisgreaterthanthisthreshold,itmeansthematchissuccessful,otherwiseitmeansthematchfails.FNMRincreaseswiththeincreaseofthethreshold,thatis,thehigherthethresholdforjudgingsimilarity,thegreatertheprobabilitythatatruefingerprintisjudgedtobefalse.Conversely,theFMRdecreaseswiththeincreaseofthethreshold,thatis,asthethresholdforjudgingthesimilarityishigher,theprobabilityofjudgingthefakefingerprintastruewillbesmaller.FARisinverselyproportionaltoFRR.AccordingtothetestresultsoftheFVCcompetitionin2004,whentheFMRis1/1000,theFNMRisabout5/100.Thatis,inthefingerprintlibraryof100fingers,if1000matchesareperformed,amatchingerrormayoccur,thatis,anacknowledgment.After100matchesareperformed,theremaybe5matchfailures,thatis,theyarenotrecognized.
EER
EER(EqualErrorRate)meansequalerrorrate.Thisparameterisgenerallynotusedinordinaryoccasions.EERismainlyusedtoevaluatetheoverallperformanceoffingerprintalgorithms.Thatis,thetwoparametersofFARandFRRareunifiedintooneparametertomeasuretheoverallperformanceofthefingerprintalgorithm.FARandFRRaretwoparametersofthesamealgorithmsystem.Puttheminthesamecoordinate.FARdecreaseswiththeincreaseofthethreshold,andFRRincreaseswiththeincreaseofthethreshold.Sotheymusthaveintersections.ThispointisthepointatwhichFARandFRRareequivalentunderacertainthreshold.Itiscustomarytousethisvaluetomeasuretheoverallperformanceofthealgorithm.Forabetterfingerprintalgorithm,itishopedthatbothFARandFRRshouldbeassmallaspossibleunderthesamethreshold.
TranslateboththeFARandFRRcurvesdownward.Atthesametime,theintersectionpointERRalsoshiftsdownward.ThesmallertheEERvalue,thehighertheoverallperformanceofthealgorithm.
BecausethecorrespondingthresholdswhenFRRandFARintersectareverysmall,thatistosay,thesimilaritythresholdatthistimeislessthan30%.Thethresholdinactualuseisatleast80%,sotheEERvalueisnotusedinpopularoccasionstodescribetheperformanceofthefingerprintalgorithm,butonlyusedincompetitionrankings.
FRRisactuallyanimportantindicatorofsystemeaseofuse.SinceFRRandFARarecontradictorytoeachother,thismakesitnecessarytoweigheaseofuseandsafetyinthedesignofapplicationsystems.Aneffectivemethodistocomparetwoormorefingerprints,therebygreatlyimprovingsystemsecuritywithoutlosingeaseofuse.
Disapprovalrate
Thedisapprovalrateisgenerallyseldomused.Infingerprintrecognitionterms,itisarelativelyvagueterm.IntheWorldFingerprintAlgorithmCompetition,thereisaparametercalledtherejectionrate,sometimescalledtherejectionrate,whichisusedtomeasurethedegreeofpickinessofthefingerprintrecognitionalgorithmonthequalityofthefingerprintimage,usingREJENROLL.Express.Inagivennumberoffingerprints,suchas100fingerprintimages,fingerprintsthatcanbesuccessfullyregisteredorcalledfilecreation,ifitis99,thenREJENROLL=1%.ForthestandardfingerprintlibrarygivenbytheFVCcompetition,mostfingerprintalgorithmscanbesuccessfullyfiled,thatis,REJENROLLis0.00%.
Onanotheroccasion,therejectionrateisusuallyinterpretedastheprobabilitythatthefingerprintidentificationsystem(includingfingerprintcollectionequipment)willnotacceptfingerprintregistration.Inthiscase,thefactorsthatrejectregistrationaremoreaffectedbytheimagingcapabilitiesofthefingerprintcollectiondevice,inadditiontothealgorithmitself.Thebetterthequalityofthefingerprintimageoutputbythefingerprintcollectiondevice,thelowertherejectionrateofthefingerprintidentificationsystem,andthelowerthequalityofthefingerprintimageoutputbythefingerprintcollectiondevice,thehighertherejectionrate.
Time
Registrationtimeisanotherindicatorusedtomeasuretheperformanceoffingerprintalgorithm.Itreferstothetimefromtheinputofthefingerprintimagetothesuccessfulestablishmentofthefingerprintfile(successfulregistration).AccordingtotheresultsoftheFVCcompetition,thegeneralfingerprintalgorithmregistrationtimeiswithin0.5seconds,whichisalsooneofthequalificationsproposedbyFVCtoparticipateintheLIGHTgroupcompetitionalgorithm.
Thematchingtimeissometimescalledthecomparisonspeed,whichisusedtoindicatethetimerequiredforthefingerprintrecognitionalgorithmtocompleteamatch.Itisthetimefromthefingerprintimageinputtotheoutputofthematchingresult.Thematchingtimeofmostalgorithmsparticipatinginthealgorithmcompetitioniswithin0.3seconds.ThisparameterandtheminimumregistrationtimeconstitutetheentryconditionsfortheLIGHTgroup.
Becausethesetimesareallaffectedbythequalityofthefingerprintimagetobetested,theaveragevalueofmultiplefingerprintlibrariesisgenerallytaken,andtheaverageregistrationtimeandaveragematchingtimearegenerallyusedasthebasisformeasurement.
Technologyintroduction
Theresearchfrom"fingerprint"to"fingerprinttechnique"hasgonethroughalongprocess.Aftertheformationoffingerprinttechnology,ithasundergonethedevelopmentandtransformationfrommanualidentificationtechnologytoautomaticidentificationtechnology.Withthedevelopmentofcomputerimageprocessingtechnologyandinformationtechnology,fingerprintrecognitiontechnologyhasgraduallyenteredthefieldofITtechnology,combinedwithmanycomputerinformationsystems,andwidelyused.
Expertsreminded
ProfessorsfromtheNationalInstituteofInformaticsinJapanremindednetizensthatifyouposeaVsignwhentakingpictures,yourfingerprintsarelikelytobestolen.Inadditiontofingerprints,facialandirisrecognitionhasalsobeenappliedtomobilephoneauthentication.Someadministrativeagenciesandenterprisesarealsousingthisinformationforattendancemanagement.Previously,inordertoobtainpersonalbiometricinformation,itwasnecessarytoapproachthepersonforshooting.However,recentlysomebiologicalinformationhasbeencirculatedontheInternet,whichgreatlyreducesthethresholdforcriminals.