Editing Fingerprint (section)

== Classification systems ==
[[File:Fingerprint Arch.jpg|150px|right|thumb|A non-tented fingerprint arch]]
[[File:Fingerprint Loop.jpg|150px|right|thumb|A fingerprint loop]]
[[File:Fingerprint Whorl.jpg|150px|right|thumb|A fingerprint whorl]]
[[File:Tented arch.jpg|right|150px|thumb|A tented fingerprint arch]]
Before computerization, manual filing systems were used in large fingerprint [[Content repository|repositories]].<ref name="roscher">{{Cite journal| last = Engert | first = Gerald J.| year = 1964| title = International Corner| journal = Identification News | volume = 14 | issue = 1}}</ref> A fingerprint classification system groups fingerprints according to their characteristics and therefore helps in the matching of a fingerprint against a large database of fingerprints. A query fingerprint that needs to be matched can therefore be compared with a subset of fingerprints in an existing [[database]].<ref name="auto"/> Early classification systems were based on the general ridge patterns, including the presence or absence of circular patterns, of several or all fingers. This allowed the filing and retrieval of paper records in large collections based on friction ridge patterns alone. The most popular systems used the pattern class of each finger to form a numeric key to assist lookup in a filing system. Fingerprint classification systems included the Roscher System, the Juan Vucetich System and the [[Henry Classification System]]. The Roscher System was developed in Germany and implemented in both Germany and Japan. The Vucetich System was developed in [[Argentina]] and implemented throughout South America. The [[Henry Classification System]] was developed in India and implemented in most English-speaking countries.<ref name="roscher"/>

In the Henry Classification System, there are three basic fingerprint patterns: loop, whorl, and arch,<ref name="henryclass">{{cite web |url         = http://www.clpex.com/Information/Pioneers/henry-classification.pdf |last = Henry|first = Edward R. |year = 1900|title = Classification and Uses of Finger Prints|location = London|publisher = George Rutledge & Sons, Ltd |url-status = dead |archive-url = https://web.archive.org/web/20061013094924/http://www.clpex.com/Information/Pioneers/henry-classification.pdf |archive-date = 13 October 2006}}</ref> which constitute 60–65 percent, 30–35 percent, and 5 percent of all fingerprints respectively.'''<ref>{{Cite journal |last1=Ross |first1=Arun |last2=Shah |first2=Jidnya |last3=Jain |first3=Anil K. |date=April 2007 |title=From Template to Image: Reconstructing Fingerprints from Minutiae Points |url=http://biometrics.cse.msu.edu/Publications/SecureBiometrics/RossShahJain_FpImageFromMinutiae_PAMI07.pdf |journal=IEEE Transactions on Pattern Analysis and Machine Intelligence |volume=29 |issue=4 |pages=544–560 |doi=10.1109/TPAMI.2007.1018 |pmid=17299213 |s2cid=777891 |s2cid-access=free |issn=0162-8828 |url-status=live |archive-url=https://web.archive.org/web/20230806203228/https://biometrics.cse.msu.edu/Publications/SecureBiometrics/RossShahJain_FpImageFromMinutiae_PAMI07.pdf |archive-date= Aug 6, 2023 }}</ref>''' There are also more complex classification systems that break down patterns even further, into plain arches or tented arches,<ref name="roscher" /> and into loops that may be radial or ulnar, depending on the side of the hand toward which the tail points. Ulnar loops start on the pinky-side of the finger, the side closer to the [[ulna]], the lower arm bone. Radial loops start on the thumb-side of the finger, the side closer to the [[radius (bone)|radius]]. Whorls may also have sub-group classifications including plain whorls, accidental whorls, double loop whorls, peacock's eye, composite, and central pocket loop whorls.<ref name="roscher" />

The "primary classification number" in the Henry Classification System is a [[Fraction (mathematics)|fraction]] whose numerator and denominator are whole numbers between 1 and 32 inclusive, thus classifying each set of ten fingerprints into one of 1024 groups. (To distinguish these groups, the fraction is ''not'' reduced by dividing out any common factors.)  The fraction is determined by ten indicators, one for each finger, an indicator taking the value 1 when that finger has a whorl, and 0 otherwise. These indicators can be written 
<math>R_t, R_i, R_m, R_r, R_l</math> for the right hand and 
<math>L_t, L_i, L_m, L_r, L_l</math> for the left hand, where the subscripts are ''t'' for thumb, ''i'' for index finger, ''m'' for middle finger, ''r'' for ring finger and ''l'' for little finger. The formula for the fraction is then as follows:

<math>{16R_i+8R_r+4L_t+2L_m+1L_l + 1 \over 16R_t+8R_m+4R_l+2L_i+1L_r + 1}.</math>

For example, if only the right ring finger and the left index finger have whorls, then the set of fingerprints is classified into the "9/3" group:

<math>{16(0)+8(1)+4(0)+2(0)+1(0) + 1 \over 16(0)+8(0)+4(0)+2(1)+1(0) + 1} = {9\over3}.</math>

Note that although 9/3 = 3/1, the "9/3" group is different from the "3/1" group, as the latter corresponds to having whorls only on the left middle finger.