Extended Fingerp

Feature Set

ANSI/NIST ITL 1-2000 Standard Wo

6 December 2005
6 December 2005

Overview Present SWGFAST Proposal, which 

additional types of fingerprint featurethose in the ANSI/NIST or IAFIS typdefinitions

 Present Extended Feature Set Com Plan for an addendum to the new AN

standard, and a committee to formu
SWGFAST 

Proposal

Steve Meagher, FBI
6 December 2005

SWGFAST Concern “AFIS technology, since its onset, ha

very limited amount of fingerprint deprint experts must rely on far more ieffecting individualizations/exclusionending ridges and bifurcations, i.e., minutiae record. SWGFAST is attemeducate and provide to the vendor cadditional features and how they are these experts.”
6 December 2005

SWGFAST goals 1. Increase fingerprint image quality.2. Increase extraction of more fingerp3. Improve the reliability of extracted f4. Improved latent print operations, bo

and in an automated system, by incidentification rates and reducing ris
6 December 2005

Key Concepts: Ridges in s Shift the AFIS approach 

away from the traditional “minutiae in sequence” to a new approach of “ridges in sequence.”
6 December 2005

Key Concepts: Exclusions Current AFIS technology focuses on 

degrees of similarity, but does not cobreadth of information needed for usnon-matches
6 December 2005

Extended FeaturesLevel 1 Featuresa. Ridge flowb. Cores and deltasc. Finer level of classification 

Level 2 Feature

a. Ridge path e

 Continuou Minutiae/ Ridge Cu Feature R

b. Open Field oc. Greater defin

 Shape an

d. Scarse. Creasesf. Incipient ridgg. Dots

Level 3 Features

a. Poresb. Edge Shapesc. Ridge/Furrow Width
Discussion o

Extended Featu

Austin Hicklin, Mitretek
6 December 2005

Overview For each feature, discuss briefly

 What is meant Practicality of definition Practicality of automatic detection

 Some of these lend themselves better to d

detection much better than others

 From a latent perspective (and for very po

latents), current AFIS is only a filter, not re

 If matchers are going to take the next step int

latent matching, matchers should take advanset of features than currently used
6 December 2005

1a: Ridge flow

 Adjacent friction ridges 

arrangement 

 Used to a limited extent 

classification in AFIS

 Role of pattern classifica

AFIS moves from rolls t

 Some AFIS use ridge flo

 Used by some matchers 

but not generally in AFIS

 Most encoders use a similar process The M1 Finger Pattern proposed standard could 

model for definition
6 December 2005

1b: Cores and Deltas

 Definition and detection will both need research

 Cores and de

in AFIS techn

 Core and del

and relations

 Using minutia

curvature wothe issue 
6 December 2005

1c: Finer level of classific The old Henry Classification was extremely beneficial to late AFIS processing uses a simplified model, due to 

 the limited benefit a finer level of classification provided The difficulty of accurate automatic pattern classification to t

 The definition of these (via Henry or NCIC) is we Automatic detection at this level is an unsolved 

generally requires rolls
6 December 2005

2a: Ridge Path (1 of 2)
6 December 2005

2a: Ridge Path (2 of 2)

 A single ridge can be 

these factors are acco

 Continuity Minutiae relationships Curvature Relationships of non-

 Definition and detection both need research
6 December 2005

2b: Open Field of Ridges 

 x
6 December 2005

2b: Open Field of Ridges 

 x  A matc

the absminutiaa space minutia

 Ther

minu

 Ther

there

 The absence of such information in IAFIS make

sensitive to prints with concavities or holes

 Readily definable and automatically detectable
6 December 2005

2c: Greater definition of mi(1 of 3)

 Shape, size, and c

minutiae are distin

 Could use a finer 

of the ridge ending configuration of th

 Use minutiae in ad

and bifurcations:

 Crossovers Trifurcations (etc)

 Definition:

 Additional types of features reasonable Shape of minutiae needs research

 Detection needs research
6 December 2005

2c: Greater definition of mi(2 of 3)

 Ridge endings ca

terms of 

 the fork of the tr the end of the tr

and/or 

 the end of the ri

the binarized im

 Bifurcations can 

the same definitioreversal. 

 Theta can be des

different distancelocation(s).

 Definition and Detection both reasonable
6 December 2005

2c: Greater definition of mi(3 of 3)

 Minu

need 

 Muc

intersimpbetw

 Bina

alreadete

 Definition and detection both reasonable
6 December 2005

2d: Scars

 Presence, lo

configuratiovery discrimin both imag

 Linear ridge 

could readily detected

 Definition and detection both need research Matching using scars needs to be fault-tolerant 

potential absence of the scar 
6 December 2005

2e: Creases

 Creases 

 between maj

skin (Flexure permanent aconfigurationbetween cap

 within friction 

can be permpermanent. 

 Flexure creases 

which provides direction to eaccrease. 

 Definition and detection need research
6 December 2005

2f: Incipient ridges

 Friction ridges not fu

which may appear sappearance, or morfully developed frict

 Rarely bifurcates Rarely/never has p May appear at time

 Distinctive in propen

and location

 Definition and detection need research in deter

how/whether to differentiate from standard ridg
6 December 2005

2g: Dots

 Dots, short ridges, 

enclosures are not IAFIS

 These are particula

 Readily definable and detectable
6 December 2005

3a: Pores

 Pores are distinc

 Size Shape/form Position on the  Number or freq

 Pores are not ge

unless both fingeresolution of 100

 Definition and detection are practical given eno See Roddy & Stosz 1999 IEEE paper “Fingerprin

statistical analysis” for discussion
6 December 2005

3b: Edge shapes

 Morphological fea

deviation, etc.) deshape of the ridge 

 Major deviations a

are usable at 500 obviously better a

 Edge features can 

Chatterjee’s edge 

 Major deviations and discontinuities: 

 Definition and detection are probably both practi

 Other features:

 Definitions can be based on Chatterjee Detection would require more research
6 December 2005

3c: Ridge/Valley width

 Measurements from 

 Edge-to-edge of a ridg Edge-to-edge of a vall Center-to-center of ad

 Special case of edge sh Possible to define and d

 Actual width of ridges 

intervals

 Major deviations in wid Discontinuities

 May be practical to define and detect, even at 5
6 December 2005

Additional Feature Types This does not preclude other types o

such as

 3d features
6 December 2005

Possible Uses Areas of improvement for feature extraction and 

algorithms, both for latent and non-latent system

 Quantification of the features actually used in lat

 Without a richer feature set, automated matchers 

advancements in latent searches

 Basis for special-purpose latent end-stage matche

require human markup of both fingerprints being cquantify similarity)

 Human examiners would be able to detail more pr

minutiae features used for comparison (for courtroetc.) 

 Improved feature set for use in modeling uniquene
6 December 2005

Next Steps Reserve block of fields in the Type-9 

use for Extended Feature Definitions

 e.g. 9.300 through 9.399

 Convene committee for Extended F

Feature Set definition

 Plan for Addendum to ANSI/NIST IT

 Target of 3Q 2006 for proposed Addendum

 FBI will be providing data sets with ma

examples (similar to NIST SD27)