Characteristics of fingerprints
We define two fingerprint features to verify fingerprints: global features and local features. General features refer to features that can be directly observed by human eyes, including:
Basic texture pattern
A cycle,
Arch,
Screw type (thread). Other fingerprint patterns are based on these three basic patterns. It is far from enough to distinguish fingerprints only by pattern types, which is only a rough classification, but it is more convenient to search fingerprints in large databases through classification.
Pattern area (pattern
Area) pattern area refers to the area on the fingerprint that contains the whole features, that is, from the pattern area, it can be distinguished which type the fingerprint belongs to. Some fingerprint identification algorithms only use the data of the pattern area.
Aetex
Fingerprint identification algorithm uses the obtained complete fingerprint instead of only using the pattern area for analysis and identification.
Core point (core
Point) is located in the progressive center of fingerprint lines and serves as a reference point for reading and comparing fingerprints.
Delta triangle points are located at the first bifurcation point or breakpoint from the core point, or at the convergence point, isolated point and inflection point of two straight lines, or point to these singular points. Triangular points provide the starting point for counting and tracking fingerprint lines.
Style line (type
A pattern line is a cross line that appears where the pattern lines around the pattern area begin to be parallel. Pattern lines are usually interrupted in a short time, but their outer lines begin to extend continuously.
Number of ridges (ridges
Count) refers to the number of fingerprint lines in the pattern area. When calculating the number of fingerprint lines, the core points and triangle points are generally connected first, and the number of lines intersecting with fingerprint lines can be considered as the number of fingerprint lines.
local color
Local features refer to the nodes on the fingerprint. Two fingerprints often have the same general features, but their local features-nodes-cannot be exactly the same.
Nodes (details
The fingerprint lines are not continuous, smooth and straight, but are often interrupted, bifurcated or discounted. These breakpoints, bifurcation points and turning points are called "nodes". It is these nodes that provide the confirmation information of fingerprint uniqueness.
The nodes on the fingerprint have four different characteristics:
1.
classify
-
There are several types of nodes, the most typical of which are endpoints and bifurcation points.
A.
End (end)
-
A striped road ends here.
B.
cusp
-
A striped road divides into two or more lines here.
C.
Bifurcation point (ridge
Divergent)
-
Two parallel lines separate here.
D.
Isolated point (point
or
Island)
-
A grain is so short that it becomes a point.
E.
A fence.
-
After a striped road is split in two, it immediately merges into one, and a small ring formed in this way is called a ring point.
F.
Short grain (short)
Ridge)
-
A particle with a short end but not a little bit,
2.
Direction (bearing)
-
Nodes can be oriented in a certain direction.
3.
bend
-
Describes the speed at which the texture direction changes.
4.
Location (location)
-
The position of nodes is described by (x, y) coordinates, which can be absolute or relative to triangle points or characteristic points.