fingerprint scan

8/16/2019 Fingerprint Scan

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Fingerprint scan


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Introduction

• Finger-scan technology utilizes thedistinctive features of the ngerprintto identify or verify the identity ofindividuals.

• Finger-scan technology is the mostcommonly deployed biometric

technology, used in a broad range ofphysical access and logical accessapplications.


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Physical and logical access

• Physical access systems monitor, restrict, orgrant movement of a person or object intoor out of a specic area. Most physical

access implementations involve entry into aroom or building ban! vaults, server rooms,control to"-ers, or any location to "hichaccess is restricted. #ime and attendance

are a common physical access application,combining access to a location "ith an auditof "hen the authentication occurred


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• $ogical access systems monitor,restrict, or grant access to data orinformation.

• $ogging into a P%, accessing datastored on a net"or!, accessing anaccount, or authenticating a

transaction are e&amples of logicalaccess. 'iometrics replace orcomplement pass"ords, PI(s, and

to!ens in logical access systems.


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• Finger-scan)s strengths include thefollo"ing

* It is a mature and proven core technology,

capable of high levels of accuracy.* It can be deployed in a range of

environments.

* It employs easy-to-use devices.

* #he ability to enroll multiple ngers canincrease system accuracy and +e&ibility.


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• Finger-scan has a handful of"ea!nesses that may impact itseectiveness for certain applications

* Most devices are unable to enrollsome small percentage of users.

* Performance can deteriorate overtime.


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%omponents

• Finger-scan systems comprise imageacquisition hardware, imageprocessing components, template

generation and matching components,and storage components.

• #hese components can be located "ithin asingle peripheral orstandalone device, or

may be spread among a peripheraldevice, a local PC,and a central server.


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• #he surface on "hich the nger is placed is called aplaten, also referred to simply as a scanner.

• Platens can be made of various materials, includingglass, plastic, silicon, and polymer.

• Proprietary coatings are used to prevent damage tothe platen itself a scratched platen reduces adevice )s ability to acuire high-uality ngerprintimages.

•/epending on the type of nger-scan technologyused, areas of contact bet"een the ngerprint andthe platen are measured through chip-basedcameras, through ultrasonic imaging,


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• 0 platen is one piece of a nger-scan module, the basicbuilding bloc! of a peripheral or standalone fnger-scandevice.

• 0 module normally contains a platen attached to a smallprinted circuit board, along "ith a standard connector thatallo"s digitized information to be transmitted to theperipheral or standalone device.

• Many of today )s nger-scan modules are capable ofperforming all system functions image acquisition,image processing, template generation, templatematching, and template storage"ithin a very smallpac!age.

• #hese modules simply send match1no-match decisions to ane&ternal application or system


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• Modules can be built into P% peripheral devices, embedded in!eyboards, lap-tops, handheld devices, or P%M%I0 cards2integrated into door control devices2 or built into standaloneterminals and readers.

• 3ventually they may be commonly ound in mobile phones, on

the surface of smart cards, and in motorized vehicles.• Depending on cost and system design requirements,

peripherals designed for P% access can perform all functionsinternally.

• 4o"-ever, in most nger-scan systems, template generation

and matching, being more processor-intensive activities,ta!e place on a local P% or central server.

• 5tandalone and physical access devices are more li!ely to havebuilt-in processing po"er, such that all of the biometric processesta!e place "ithin the device itself


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• #he results of a nger-scan match are transmittedfrom the biometric system in the proper format forauthentication to logical or physical accesssystems.

• Finger-scan systems may be tightly integrated "iththese e&ternal systems

• 6applications, operating systems, smart cardauthentication components, electronic door loc!s,

mobile phones7 or may simply pass a pass"ord tothe application. #his integration piece is ane&tremely important part of any biometric system


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4o" Finger-5can #echnology 8or!s

• #here are ve stages involved innger-scan verication andidentication

• ngerprint image acuisition,

• image processing,

• location of distinctive characteristics,

• template creation, and

• template matching.


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9. Image 0cuisition

• #he rst challenge facing a nger-scan system isto acuire a high-uality image of thengerprint. Image uality is measured in dotsper inch 6/PI7

• more dots per inch means a higher-resolutionimage.

• #oday)s nger-scan

•

peripherals can acuire images of :;; /PI, thestandard for forensic-uality ngerprinting.

• #he lo"est /PI generally found in the mar!et isin the


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• Image acuisition is a major challenge for nger-scandevelopers, because ngerprint uality can varysubstantially from person to person and from nger to nger.

• 5ome populations are more li!ely than others to have faint ordi=cult-to-acuire ngerprints, "hether due to "ear and tearor physiological traits.

• In addition, environmental factors can impact imageacuisition. In very cold "eather, the oils normally found ona ngerprint 6"hich ma!e for better imaging7 dry up, suchthat ngerprints can appear faint.

• >sers may need to press more rmly or even rub the ngerinto their opposite palm to ensure that a uality image isacuired.


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"or!ing

• For a nger-scan image to act as an eectiveenrollment, the center of the nger-print mustbe placed on the platen.

•

Many users unfamiliar "ith the technology "illplace their nger at an angle, such that onlythe upper portion of the nger-print appears.

• #his results in fe"er distinctive features being

located during enrollment and verication,reducing the li!elihood of successful operation


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• 0n additional factor in image acuisition that can aecta system)s accuracy and performance is the size o theplaten.

• ?ver time, nger-scan vendors have developed smaller

and smaller platens in order to manufacture smallerdevices and to reduce costs.

• @ery small platens acuire a smaller portion of thengerprint, meaning that less data is available to create

• and match templates.

• >sers "ith large ngers may also nd it di=cult topresent their ngerprint in a consistent fashion, leadingto false rejections


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A. Image Processing

• ?nce a high-uality image is acuired, it must beconverted to a usable format.

• Image processing subroutines eliminate gray areasfrom the image by converting the ngerprint image

)s gray pi&els to "hite and blac!, depending on theirpitch.

• 8hat results is a series of thic! blac! ridges 6theraised part of the ngerprint7 contrasted to "hite

valleys.• #he ridges are then thinned from appro&imately : to

B pi&els in "idth do"n to a single pi&el, for preciselocation of features


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fingerprint scan

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