seminar code
04-08-2014, 11:43 AM
The Effect of Force on Fingerprint Image Quality and Fingerprint Distortion
[attachment=66542]
ABSTRACT
The purpose of this paper is to investigate fingerprint quality and quality
problems due to nonlinear elastic distortion. The effect of force on
fingerprint quality was studied using computation and analysis of the
correlation coefficient r between the fingerprint quality score and force. The
correlation analysis results show that fingerprint quality is significantly
attributed to force. Based on the U test, a comparative study between male
and female students about the fingerprint quality was conducted. At the 0.05
level of significance, there is a significant difference between male and
female students in the fingerprint quality of the flat left thumb at a greater
force level and in the fingerprint quality of the slap left fingers at all force
levels.
INTRODUCTION
Fingerprint recognition is one of the foremost and most often used methods in biometrics. It has
been used in criminal identification, computer access or login security, in a wide area of healthcare systems,
and in Homeland Security for e-passports and border access control. Since September 11, 2001, fingerprint
recognition has become an advanced tool to fight against terrorism.
A flat fingerprint (also known as plain fingerprint or plain impression) can be obtained if a finger is
pressed down on a platen (scanner) but not rolled. Rolled fingerprint images are obtained by rolling a finger
from one side to the other (“nail-to-nail”) in order to capture all of the ridge details of a finger [1]. A slap
fingerprint refers to fingerprints simultaneously captured in a single image by pressing four fingers of one
hand onto a platen or a fingerprint card. Slaps are also known as four finger simultaneous plain impressions.
The four fingers are little finger, ring finger, middle finger, and index finger [2]. Flat fingerprints cover a
smaller area than rolled fingerprints; have fewer minutiae; but are less distorted; and therefore have clearer
ridges [3]. Flat fingerprints can be acquired quickly with little operator training. Rolled fingerprints provide a
great deal of information, but properly rolling fingerprints is a slow process and operators must be trained to
collect good quality rolled fingerprints [4].
Figure 1 shows a flat fingerprint and a rolled fingerprint and their image quality scores of the author
of this paper. The fingerprints and the image quality scores were captured using the ID 500 10-Print Live
Scan System [2].
RESULTS AND ANALYSIS
3.1. Data and Descriptive Statistics for Fingerprint Quality Scores
This fingerprint experiment was conducted in September 2012. 24 participants were university
students (14 male students and 10 female students) and were 18-25 years old. Each student’s fingerprint
quality scores for the flat left thumb at seven force levels were obtained. The seven force levels are: 0.98N,
3.47N, 5.87N, 9.39N, 11.97N, 17.22N, and 21.17N. Each student’s fingerprint quality scores for slap left
fingers at the next seven force levels were obtained. The next seven force levels are: 3.60N, 6.18N, 9.39N,
11.97N, 17.22N, 21.17N, and 24.24N. Figure 4 shows a student’s fingerprint quality scores of the flat left
thumb at seven force levels; Figure 5 shows the same student’s fingerprint quality scores of the slap left
fingers at the next seven force levels.
In Figure 4 and Figure 5, the fingerprint quality score increases as force increases; then decreases as
force increases. Force has a great impact on fingerprint quality. There is no incremental benefit in terms of
fingerprint image quality when force is greater than a value. The value is 11.97 N in Figure 4 and 17.22N in
Figure 5. Among the 24 students, eight students' flat fingerprint quality scores got to maximal values when
the force is 9.39N; ten students’ slap fingerprint quality scores got to maximal values when the force is
11.97N
Non-parametric Analysis for Male Students and Female Students’ Fingerprint Quality
14 male students and 10 female students participated in the fingerprint experiment. The author
conducted a comparative study between the male and female students to compare the flat fingerprint quality
of the left thumb at seven force levels and the slap fingerprint quality of left fingers at the next seven force
levels, respectively. The author formulated the following null hypothesis:
There is no statistically significant difference in the fingerprint image quality between male and
female students. The outcome is: the hypothesis is accepted or rejected at ߙ ൌ 0.05. ߙ is the level of
significance.
The author used a non-parametric method to test the hypothesis. It is called the U test, the Wilcoxon
test, or the Mann-Whitney test, named after the statisticians who contributed to its development. The major
advantage of non-parametric methods is that no specific assumptions (such as normal distribution) about the
population or the sample are required. Therefore, non-parametric methods can be used under more general
conditions [15]. The U test is illustrated as follows:
Suppose that ܹଵ is the sum of the ranks of the values of the first sample (female students); ܹଶ is the
sum of the ranks of the values of the second sample (male students) ݊ଵand ݊ଶ are the first sample size and the
second sample size, respectively. The statistic ܷ is decided based on the following ܷଵ ܷଶstatistics:
CONCLUSION
Fingerprint images and quality scores captured through the ID 500 10-Print Live Scan System for
both the flat left thumb and the slap left fingers indicate that too much or too little force leads to fingerprint
quality problems. There are some breaks in the fingerprint image in the case of too little force; there are some
dark areas in the fingerprint image and nonlinear elastic distortion in case of too much force.
Although dry finger skin, diseased fingers, sweaty fingers, or increased humidity, etc., can cause
poor fingerprint images, the fingerprint quality of the 24 students in this study is strongly attributed to force
(not other factors) according to the calculated correlation coefficient r and the correlation analysis. Too much
force causes bad fingerprint quality because of large nonlinear elastic distortion that resulted from force.
The results obtained from the non-parametric method based on the U test indicate that there is a
significant difference between male and female students in the fingerprint image quality of the flat left thumb
at a greater force level and in the fingerprint image quality of the slap left fingers at all force levels when the
level of significance ߙ is 0.05. Female students' fingers are softer (especially the little finger for the slap
fingerprint). It is easier for softer fingers to be affected by force and produce greater non-linear elastic
distortion, which leads to the significant difference between male and female students
[attachment=66542]
ABSTRACT
The purpose of this paper is to investigate fingerprint quality and quality
problems due to nonlinear elastic distortion. The effect of force on
fingerprint quality was studied using computation and analysis of the
correlation coefficient r between the fingerprint quality score and force. The
correlation analysis results show that fingerprint quality is significantly
attributed to force. Based on the U test, a comparative study between male
and female students about the fingerprint quality was conducted. At the 0.05
level of significance, there is a significant difference between male and
female students in the fingerprint quality of the flat left thumb at a greater
force level and in the fingerprint quality of the slap left fingers at all force
levels.
INTRODUCTION
Fingerprint recognition is one of the foremost and most often used methods in biometrics. It has
been used in criminal identification, computer access or login security, in a wide area of healthcare systems,
and in Homeland Security for e-passports and border access control. Since September 11, 2001, fingerprint
recognition has become an advanced tool to fight against terrorism.
A flat fingerprint (also known as plain fingerprint or plain impression) can be obtained if a finger is
pressed down on a platen (scanner) but not rolled. Rolled fingerprint images are obtained by rolling a finger
from one side to the other (“nail-to-nail”) in order to capture all of the ridge details of a finger [1]. A slap
fingerprint refers to fingerprints simultaneously captured in a single image by pressing four fingers of one
hand onto a platen or a fingerprint card. Slaps are also known as four finger simultaneous plain impressions.
The four fingers are little finger, ring finger, middle finger, and index finger [2]. Flat fingerprints cover a
smaller area than rolled fingerprints; have fewer minutiae; but are less distorted; and therefore have clearer
ridges [3]. Flat fingerprints can be acquired quickly with little operator training. Rolled fingerprints provide a
great deal of information, but properly rolling fingerprints is a slow process and operators must be trained to
collect good quality rolled fingerprints [4].
Figure 1 shows a flat fingerprint and a rolled fingerprint and their image quality scores of the author
of this paper. The fingerprints and the image quality scores were captured using the ID 500 10-Print Live
Scan System [2].
RESULTS AND ANALYSIS
3.1. Data and Descriptive Statistics for Fingerprint Quality Scores
This fingerprint experiment was conducted in September 2012. 24 participants were university
students (14 male students and 10 female students) and were 18-25 years old. Each student’s fingerprint
quality scores for the flat left thumb at seven force levels were obtained. The seven force levels are: 0.98N,
3.47N, 5.87N, 9.39N, 11.97N, 17.22N, and 21.17N. Each student’s fingerprint quality scores for slap left
fingers at the next seven force levels were obtained. The next seven force levels are: 3.60N, 6.18N, 9.39N,
11.97N, 17.22N, 21.17N, and 24.24N. Figure 4 shows a student’s fingerprint quality scores of the flat left
thumb at seven force levels; Figure 5 shows the same student’s fingerprint quality scores of the slap left
fingers at the next seven force levels.
In Figure 4 and Figure 5, the fingerprint quality score increases as force increases; then decreases as
force increases. Force has a great impact on fingerprint quality. There is no incremental benefit in terms of
fingerprint image quality when force is greater than a value. The value is 11.97 N in Figure 4 and 17.22N in
Figure 5. Among the 24 students, eight students' flat fingerprint quality scores got to maximal values when
the force is 9.39N; ten students’ slap fingerprint quality scores got to maximal values when the force is
11.97N
Non-parametric Analysis for Male Students and Female Students’ Fingerprint Quality
14 male students and 10 female students participated in the fingerprint experiment. The author
conducted a comparative study between the male and female students to compare the flat fingerprint quality
of the left thumb at seven force levels and the slap fingerprint quality of left fingers at the next seven force
levels, respectively. The author formulated the following null hypothesis:
There is no statistically significant difference in the fingerprint image quality between male and
female students. The outcome is: the hypothesis is accepted or rejected at ߙ ൌ 0.05. ߙ is the level of
significance.
The author used a non-parametric method to test the hypothesis. It is called the U test, the Wilcoxon
test, or the Mann-Whitney test, named after the statisticians who contributed to its development. The major
advantage of non-parametric methods is that no specific assumptions (such as normal distribution) about the
population or the sample are required. Therefore, non-parametric methods can be used under more general
conditions [15]. The U test is illustrated as follows:
Suppose that ܹଵ is the sum of the ranks of the values of the first sample (female students); ܹଶ is the
sum of the ranks of the values of the second sample (male students) ݊ଵand ݊ଶ are the first sample size and the
second sample size, respectively. The statistic ܷ is decided based on the following ܷଵ ܷଶstatistics:
CONCLUSION
Fingerprint images and quality scores captured through the ID 500 10-Print Live Scan System for
both the flat left thumb and the slap left fingers indicate that too much or too little force leads to fingerprint
quality problems. There are some breaks in the fingerprint image in the case of too little force; there are some
dark areas in the fingerprint image and nonlinear elastic distortion in case of too much force.
Although dry finger skin, diseased fingers, sweaty fingers, or increased humidity, etc., can cause
poor fingerprint images, the fingerprint quality of the 24 students in this study is strongly attributed to force
(not other factors) according to the calculated correlation coefficient r and the correlation analysis. Too much
force causes bad fingerprint quality because of large nonlinear elastic distortion that resulted from force.
The results obtained from the non-parametric method based on the U test indicate that there is a
significant difference between male and female students in the fingerprint image quality of the flat left thumb
at a greater force level and in the fingerprint image quality of the slap left fingers at all force levels when the
level of significance ߙ is 0.05. Female students' fingers are softer (especially the little finger for the slap
fingerprint). It is easier for softer fingers to be affected by force and produce greater non-linear elastic
distortion, which leads to the significant difference between male and female students