Patterns of dermatoglyphics have been an object of interest to
people for long time now, and thanks to that they have been
examined and described quite extensively. Unfortunately, the
approach to this subject developed by dactylography mainly for
needs of criminology does not lend itself to easy mathematical
formalisation. In practice this means that classic methods of
fingerprints' recognition are not suitable for direct
implementation in form of computer algorithms. In spite of this
obvious fact, authors of many existing solutions - known and
described in the literature dealing with ways of numerical
processing of fingerprints, have attempted, usually in a direct
way, eventually with small departures from that, to apply classic
dactylographics formulas. Such approach has led to creation of
very complicated programmes, which can analyse an image of a
finger with employment of sophisticated methods, primarily
so-called mathematical morphology. So complicated a solution of
the problem precludes creation of simple programmes, unsusceptible
to input errors (see [1]).
It seems that one of
the basic problems hindering construction of algorithms for
analysis of fingerprint images was lack of good mathematical model
of the structure of dermatoglyphics. To create such a model one
should understand first the essence of the phenomenon, and also to
develop methods of its reliable and easy algorithmisation. As a
starting point in our attempts of creation of such a model we
selected the problem of synthesis of pattern of dermatoglyphics -
chiefly minutiea. Everything indicated that resolving of this
problem would be the key to solving of other problems.
Over the period of
several years we have carried out many numerical experiments,
which at the end bore fruits in form of creation of suitable model
of a finger. On this basis there was created an original algorithm
of synthesis of images of dermatoglyphics, and in particular all
the possible arrangements of so called minutiea. The model allows
to looks at digital coding of a fingerprint from a new point of
view: not only as a set of pixels but some (quite simple)
two-dimensional function of very interesting qualities. It also
enables mathematical cataloguing of minutiea and types of patters,
and this means revolution in methods of analysing, processing and
compression of fingerprint images. The below presents synthetic
images of minutiea, which are met most often (according to [2]),
along with the table showing our conventional numerical
classification (number and type of bifurcations):
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Drg. 1 |
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Drg. 2 |
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Drg. 3 |
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Drg. 4 |
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Drg. 5 |
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Drg. 6 |
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Drg. 7 |
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Drg. 8 |
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Drg. 9 |
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Drg. 10 |
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Drg. 11 |
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Drg. 12 |
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Drg. 13 |
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Drg. 14 |
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Drg. 15 |
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Drg. 16 |
| Drg.1 |
Beginning or ending |
L |
Drg.9 |
Double
whorl |
RLRL |
| Drg.2 |
Singel
bifurcation |
L |
Drg.10 |
Singel
bridge |
RL |
| Drg.3 |
Double
bifurcation |
LL |
Drg.11 |
Twin
bridge |
RLLR |
| Drg.4 |
Triple
bifurcation type 1 |
LLL |
Drg.12 |
Interval |
RL |
| Drg.5 |
Triple
bifurcation type 2 |
LLL |
Drg.13 |
Point |
RL |
| Drg.6 |
Triple
bifurcation type 3 |
LLL |
Drg.14 |
Through
line |
LR |
| Drg.7 |
Hook |
RL |
Drg.15 |
Crossing |
LR |
| Drg.8 |
Single
whorl |
RL |
Drg.16 |
Side
contact |
RL |
Due to commercial
potential of the method, we cannot yet describe the methods of
synthesis in detail, but to present its capabilities we can
provide a demonstration programme Fingerprint
Creator generating an extensive range of dermatoglyphic
patterns. User of the programme can set by himself, among others,
such parameters of synthesis as:
- type of pattern (concentric,
curved, looped)
- number of munitions
- density of dermatoglyphics
- width of dermatoglyphics
- shift and rotation of centre
of the pattern
Programme in DOS
version enables recording of the generated pattern in one of three
format (and two for Windows
version):
| Form of
data |
Size of
data (bytes) |
Extension
of data file |
| One-bit bitmap |
8222 |
*.bmp |
| Matrix of
"pure" bytes |
65536 |
*.fin |
| Set of
synthesis parameters |
6 |
*.par (*.fpp
for Windows) |
Attention should be
given to the last form, and concretely the size of the set, which
is created with that. The synthesis method created by us needs
only 6 bytes to generate one from several million images of
dermatoglyphics! Although this version of the programme cannot
generate all the possible patters, but we think we will be able to
achieve that soon. Assuming (with overestimation) that the number
of possible human fingerprints can reach 100 milliard, it can be
easily calculated that the minimum number of bytes needed for
numbering all the patterns will not exceed 6, because 100 milliard
= 1014 < 2566 = 6 bytes. As it can be
easily noticed creation of a catalogue with all the possible
patterns and referring to such classification is in practice
impossible to be carried out. It is possible, however, to use a
finger's number if it will be a univocal parameter of the
synthesis' parameter. Below are presented examples of synthetic
images of fingers generated with Fingerprint
Creator:
The basic goal of
creation of a finger's model was however the necessity of
development of new, better algorithms of analysis. And indeed -
knowing the mathematical description of artificial patters - it
was possible to create a method of processing and analysis of
images of real fingerprints. It contains algorithms of recognition
of minutins (including their directions and types) directly onto
the non-filtering, fully dynamic (full grey level) image of a
finger. Because we do not use binarisation, skeletonisation or
other similar methods, we do not have any problems with loosing of
information present in those processes, and the minutiea, which
are recognised, are really the very ones in almost 100% (classic
algorithms often detect a great number of false minutiea, it
sometimes occurs that even largely above 50%). An additional trump
in the analysis method employed by us is possibility of their
implementation in the form of very quick algorithms. On their
basis we managed to create very effective methods of filtration,
allowing cleaning dermatoglyphics from any "defects."
Their employment decreases natural redundancy of an image
resulting in the image of the real finger looking somewhat "synthetic,"
although it still possesses all the properties of the original
essential for its recognition.
Our method also
allows a broadly understood "finger engineering," for
unrestrained ingeration in the image's structure. For example with
its assistance additional minutiea or lines can be positioned in
any given place in the real picture of the finger without altering
the rest of the structure. Also it is possible, conversely, to
deprive the finger's image of several or all the real minutiea.
Below please find an example of an effect of our algorithm's
application - searching for minutiea on an ultrasonic image of
dermatoglyphics. The shown image comes from our ultrasonic
holographic camera.
It should be
emphasised that the processing methods created by us perform very
well also on other types of images and are of relatively low
sensitivity to the character of input data. So far we have
successfully tested them on:
- ultrasonic images from our own
ultrasonic hollographic camera;
- ultrasonic images obtained
with a microscopic method (scanning with a focused beam);
- optical images from many
different devices employing an effect of full internal
reflection or light diffusion on the contact surface with the
finger;
- optical images from devices of
"touchless" type that see directly the finger's
surface;
- scanned ink generated images;
- images from a piroelectric
reader by Thomson-CSF;
- synthetic patterns of "Fingerprint
Creator" programme.
Due to particularly
effective way of analysis of dermatoglyphics and, primarily, a
systematic approach to this issue, we are in the position to
propose much more from manufacturers of classic programmes of
fingers' recognition. We are also ready to adapt our algorithms in
the case of other finger's readers of a especial character of
data. Should you express your interest in our offer, please contact
us.
