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Fingerprint Patterns and Minutiae

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FINGERPRINTS

Rahul

3/7/20263 min read

Fingerprint Patterns and Minutiae

Objectives

Types of Fingerprint Patterns
Minutia

Types of Fingerprint Patterns

Francis Galton (1892) for the first time distinguished and classified three main pattern types on fingers. They are whorl, loop and arch.
However, Henry (1900) proposed a four classification system for fingerprints. He classified the types as arch, loop, whorl and composite. It is more widely used and is the base of the modern classification system.
So mainly fingerprint patterns are:
- Arches – Plain Arch and Tented Arch
- Loop – Radial Loop and Ulnar Loop
- Whorl – Plain Whorl and Composite Whorl

Arch Fingerprint Pattern

In this pattern, ridges enter on one side of the fingerprint pattern and exit on the opposite side.

The Arch pattern has two subtypes:

Plain Arch (A)

It is the simplest of all fingerprint patterns.
The plain arch ridges enter on one side of the impression and flow or tend to flow out on the other side with a slight rise or wave in the center.

Tented Arch (T)

Ridges enter on one side of the impression and flow or tend to flow out on the other side with a tent-like appearance in the center.

Important Point

Arches are present in only 5% of the population and are considered rare.

Loop Fingerprint Pattern

One of the most common patterns, found in 60–65% of the population.

A Loop is the type of fingerprint pattern in which one or more ridges enter on either side of the impression, recurve, touch or pass an imaginary line drawn from delta to core, and terminate or tend to terminate towards the same side where the ridge entered.

Important Feature

A loop pattern contains only one delta.
Loops are subdivided into two main types:

1. Radial Loop (RL)

It is called radial because ridges flow or terminate in the direction of the radius bone, i.e., towards the thumb of the forearm.

2. Ulnar Loop (UL)

It is called ulnar because the ridges flow or terminate in the direction of the ulna bone, i.e., towards the little finger of the forearm.

Whorl Fingerprint Pattern

A whorl is characterized by a circular pattern in which one or more ridges revolve around the core forming a complete circle.
A line drawn between two deltas crosses the curve of the whorl.

Important Points

At least two deltas are present within a recurve in front of each whorl type.
Whorls are the most complex of the three main fingerprint patterns.
According to Henry, there are two kinds of whorls:
1. True (Plain) Whorl
2. Composite Whorl

1. Plain / True Whorl

A true whorl possesses two tri-radius (deltas).
At least one ridge makes a complete circuit, which may be:
- Spiral
- Oval
- Circular
- Any variant of a circle
The ridge may revolve in clockwise or anticlockwise direction.

2. Composite Whorl Pattern

Composite patterns are compound patterns in which two or more designs, each conforming to the general aspect of one of the simpler types, are combined in the pattern area.

Characteristics

Two or more tri-radius (deltas) are present.
There are four main types of composite patterns.

Types of Composite Patterns

I. Central Pocket Loop

The line drawn between two deltas does not cross the curve of the whorl.

II. Lateral Pocket Loop

Similar to the central pocket loop but not located at the center.
It lies on one side of the pattern.

III. Twin Loop

A combination of Loop + Loop pattern.

IV. Accidentals

Very rare and occur by chance.
These patterns consist of a combination of two different types of patterns, except plain arch.

Examples include:

Whorl + Loop
Tented Arch + Loop
Triple combinations etc.

Minutia

Minutiae are unique and distinctive ridge characteristics where ridges either end or abruptly split.
These points are used for individual identification in fingerprint comparison.
There are various types of minutiae, which are generally shown through diagrams in fingerprint analysis.