Fingerprints - Eter - Biometric Tecnologies


The Dactyloscopy is the science that studies the methods of recognizing a person by analyzing his fingerprints.

In the context of biometric technologies, the fingerprint recognition is certainly the system that is most prevalent in both commercial and governmental, probably because the cost of the equipment is smaller and because the study of fingerprints is more consolidated, has more ancient origins in time.



  • è is a science that has existed for over 100 years
  • fingerprints are "biometric keys" that are unique to each individual and unchanging over time
  • the fingerprint does not create confusion in the user
  • the automatic fingerprint recognition are:
    • Easy to use
    • Of a size and cost controlled
    • Can provide high performance

Features of the trail

Immutability: there are more than 40 features that can be quantified and used to identify an individual

Classification: ci sono piĆ¹ di 40 caratteristiche che possono essere quantificate e usate per identificare un individuo.

Uniqueness: no two fingerprints alike, even among identical twins.



  1. Survey of significant details
  2. Encoding
  3. Retention


  1. Survey of significant details
  2. Comparison with the data stored
  3. Acceptance / Fail


What is the Dactyloscopy

For dactyloscopy refers to the study of the dermal papillary ridges-protrusions existing on the entire inner surface of the hands (fly zone) and of the lower limbs (plantar area). This study, in the judicial branch of the discipline, is aimed at a judgment of identity (positive or negative) meaning that the identity fingerprint is the perfect equality of two terms in comparison to their derivation from the same subject.

Historical Background

The first science-based approach to the study of papillary impressions is due to Italian Marcello MALPIGHI that, in 1664, studied the characteristics of the epidermis, identifying the 5 layers that comprise it. In 1823, by the PURCKINJE we have the first claim on the possibility of classifying fingerprints, which is a practical response by William Janes Hershell, Governor of Bengal, who in 1858 introduced in that region the practice of affixing a fingerprint on the contracts signed by indigenous illiterate, like the law TAHIO Japanese 702 which prescribed such display in requests for divorce. It was through this experience that Hershell proposed in 1877 the adoption of a register of fingerprints for prisoners, endorsed in 1892 by Francis Galton, who proposed his own system of classification in which concepts are inspired by all the following up to today. The first effective application of fingerprint identification systems is, however, in 1901 by Juan Vucetich, police chief of La Plata, who had the merit to simplify the classification systems.

Characteristics of papillary impressions

Papillary impressions are formed completely by the 4th month of intrauterine life and remain unchanged until the post-mortem decay. Any permanent injuries will themselves become part of the distinctive features of the impression. The accidents and the overall design of the papillary impressions have total uniqueness and are well suited to the classification criteria orders.


Looking at the drawing (dermatoglyph) formed by involutions of dermal ridges present on the fingertips, we can distinguish three systems of lines corresponding to the same areas:

  1. system or basal area: from the interline joint between the second phalanx and fingertip average trend parallel to this
  2. system or marginal zone: follow and surround the finger in the radial, ulnar, and upper or apical
  3. system or zone central nucleus: of the impression, not always present, it is bordered by the other two systems.

The presence and the provision of these three systems gives rise to four types of figures universally accepted:

Concentric bidelta:

When the intersection of the three systems, in both the ulnar and radial directions, determines the formation of two triangles (delta) central closed and concentric

Composite bidelta:

equal to the previous one, except that in the central area, which has two different bundles of lines with opposite openings

Monodelta Right and Left:

Properly ulnar and radial, has a central zone open on one side, and thus the formation of a delta only on the opposite side

ADELTA or anuclears:

missing in the central area and therefore without delta.

Components of the impression

The imprint is usually made up of papillary natural secretions (and possibly contaminated) produced by three types of superficial glands: eccrine and apocrine sweat glands and sebaceous glands. The palmar and plantar surfaces are characterized only by eccrine glands.

The main components are amino acids, urea, uric acid, fatty acids and inorganic components such as chlorides, sulfates, phosphates and water (main component greater than 98%)

Ways of highlighting

The methods currently in use for the highlight of the latent prints, i.e. those not directly perceptible, are:

  • mechanical (dust)
  • Chemicals (cyan-acrylate, Iodine, Ninhydrin)
  • fluorescence (Ninhydrin and metal salts, DFO, fluorescent powders)
  • physical (metal)


One of the most debated issues is the minimum number of accidentality that an imprint papillary, albeit partial, must offer so that we can establish its identity with other concerned. The probabilistic approach Balthazard initial estimated in 16 characteristic points a legally valid threshold indicating less than 1 in 17 billion chance to find the same combination of 16 minutiae. This theory has been implemented in its original form by the Italian Law with the judgments of 14.11.1959 of the 2nd Chamber of the Supreme Court and the Sect.4 ^ 23.03.1989. This purely quantitative assessment now seems outdated, having shifted the attention to the specific representation of each accidental and coming to the conclusion formulated in 1973 IAI (International Association for Identification) that denies the existence of a minimum number of common randomness necessary to affirm a judgment of identity.

As already recognized by many foreign legislation, the qualitative analysis of randomness and their mutual location within fingerprints are detected in a pattern of systems apical, basal and central allows you to make valid comparisons, even if it only for the exclusion or for the continuation of the investigations, also with a number of accidentality reduced, especially if the evaluation of accidentality is connected to statistical investigations on their dissemination. Computer and fingerprint.

Computer and fingerprint

The possibility to catalogue fingerprints, a fundamental requirement for any kind of systematic research, allows you to take advantage of the support provided by information technology for creating archives efficient, streamlined and easy to read even remotely. On the basis of these considerations has been established and developed an international project called AFIS (Automatic Fingerprint Identification System), which has led to various local solutions. We can basically say that is based on creating a DB scanned fingerprints that are cataloged according to criteria fingerprint. Different implementations differ on the methods used to optimize the space required to store the fingerprints and search algorithms. It should be considered that a city like Milan normally has an archive fingerprints afferent about 250,000 people and the only recording of the 10 papillary prints at 500 dpi and 256 gray tones with dimensions 40 x 40 mm uncompressed would require at least 15,000,000 Mb!


At present, the type of work engineers and scientists working in the field is divided into two main sections. Activity intended immediate and one directed to lay the foundation for development in the short to medium term.

As regards the work "current" or "present" are intended mainly to improve the techniques of highlighting the latent prints, and then mainly affect the chemical, physical, while for the "Future" the area of interest is that of resolution enhancement of fingerprints, after highlighting, using electronic instruments and dedicated algorithms. A border was opened to the use of information technology not as a mere support but as a true business partner. The creation of expert systems capable of carrying out an analysis of the impression as a Dactyloscopist, according to the criteria of semantic analysis, it is a perspective that opens to fingerprint application fields for costs and practical difficulties.

The spread of this kind of expert systems is increasing in the world for a variety of applications, both governmental (electronic voting, census of citizens and immigration) and trade in the most common access control applications (companies, banks, airports for employees or frequent flyer , private homes in domotic applications or activation of the alarm).

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