1. A display control apparatus comprising: setting means for setting a parameter according to an input of a user; 5 determination means for determining, for each of areas of a fingerprint image obtained by dividing the fingerprint image, whether quality of a ridge pattern in the area is satisfactory or not based on the parameter; and first display control means for making display means display the fingerprint image according to a result of the determination. 10

2. The display control apparatus according to Claim 1, wherein the setting means sets a regularization parameter in a regression with regularization according to the input, and the determination means performs fitting for the ridge pattern by using a 15 plurality of template images by the regression with regularization based on the regularization parameter, and determines whether the quality of the ridge pattern is satisfactory or not according to a result of the fitting.

3. The display control apparatus according to Claim 2, wherein the 20 regression with regularization is a Lasso regression.

4. The display control apparatus according to Claim 2 or 3, wherein the template images are emphasized images obtained by applying filters capable of extracting stripe patterns to the fingerprint image. 25

5. The display control apparatus according to any one of Claims 1 to 4, further comprising second display control means for displ aying a slider bar on the display means, wherein the setting means sets the parameter according to a position of a slider on 30 the slider bar.

6. A display control method comprising: setting, by a computer, a parameter according to an input of a user; determining, by the computer, for each of areas of a fingerprint image 16 obtained by dividing the fingerprint image, whether quality of a ridge pattern in the area is satisfactory or not based on the parameter; and making, by the computer, display means display the fingerprint image according to a result of the determination. 5

7. The display control method according to Claim 6, wherein a regularization parameter is set in a regression with regularization according to the input, and fitting for the ridge pattern is performed by using a plurality of template 10 images by the regression with regularization based on the regularization parameter, and it is determined whether the quality of the ridge pattern is satisfactory or not according to a result of the fittin g.

8. A non-transitory computer readable medium storing a display control 15 program for causing a computer to perform: a process for setting a parameter according to an input of a user; a process for determining, for each of areas of a fingerprint image obtained by dividing the fingerprint image, whether quality of a ridge pattern in the area is satisfactory or not based on the parameter; and 20 a process for making display means display the fingerprint image according to a result of the determination.

Technical Field
[0001]
The example embodiments relate to a display control apparatus, a method,
and a non-transitory computer readable medium storing a program, and in
10 particular to a technology for displaying a fingerprint image.
Background Art
[0002]
Patent Literature 1 discloses a biometric authe ntication apparatus that
15 divides a fingerprint image into a plurality of areas and, except for unclear areas
thereof, makes corrections to the areas. The biometric authentication apparatus
disclosed in Patent Literature 1 can prevent erroneous feature val ues from being
extracted from the unclear areas.
20 Citation List
Patent Literature
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2019-109619
25
Summary of Invention
Technical Problem
[0004]
It should be noted that there has been a problem that it is difficult for an
30 operator to appropriately classify areas in a fingerprint image into high quality
parts and low-quality parts.
[0005]
The present disclosure has been made in order to solve the above -
described problem, and an object thereof is to provide a display control apparatus,
3
a method, and a program capable of displaying a fingerprint image based on an
input of a user.
Solution to Problem
5 [0006]
A display control apparatus according to the present disclosure includes:
setting means for setting a parameter according to an input of a user;
determination means for determining, for each of areas of a fingerprint image
obtained by dividing the fingerprint image, whether quality of a ridge pattern in
10 the area is satisfactory or not based on the parameter; and first display control
means for making display means display the fingerprint image according to a
result of the determination.
[0007]
A display control method according to the present disclosure includes:
15 setting, by a computer, a parameter according to an input of a user; determining,
by the computer, for each of areas of a fingerprint image obtained by dividing the
fingerprint image, whether quality of a ridge pattern in the area is satisfactory or
not based on the parameter; and making, by the computer, display means display
the fingerprint image according to a result of the determination.
20 [0008]
A display control program according to the present disclosure causes a
computer to perform: a process for setting a paramet er according to an input of a
user; a process for determining, for each of areas of a fingerprint image obtained
by dividing the fingerprint image, whether quality of a ridge pattern in the area is
25 satisfactory or not based on the parameter; and a process for making display
means display the fingerprint image according to a result of the determination.
Advantageous Effects of Invention
[0009]
30 According to the present disclosure, it is possible to provide a display
control apparatus, a method, and a program capable of displaying a fingerprint
image based on an input of a user.
Brief Description of Drawings
4
[0010]
Fig. 1 is a block diagram showing a configuration of a display control
apparatus according to a first example embodiment;
Fig. 2 is a flowchart showing a flow of a display control method according
5 to the first example embodiment;
Fig. 3 is a block diagram showing a configuration of a display control
apparatus according to a second example embodiment;
Fig. 4 shows an example of Gabor filters used to generate template
images;
10 Fig. 5 shows an example of a fingerprint image;
Fig. 6 shows an emphasized image obtained by applying a Gabor filter to a
fingerprint image;
Fig. 7 shows a composite image obtained by combining a plurality of
emphasized images having different directions;
15 Fig. 8 shows an example of a display image when a parameter is set to a
low value;
Fig. 9 shows an example of a display image when the parameter is set to a
medium value;
Fig. 10 shows an example of a display image when the parameter is set to
20 a high value; and
Fig. 11 shows an example of a display screen displayed by the display
control apparatus according to the second example embodiment.
Example Embodiment
25 [0011]
An example embodiment according to the present discl osure will be
described hereinafter in detail with reference to the drawings. The same
reference numerals (or symbols) are assigned to the same or corresponding
elements throughout the drawings, and redundant descriptions thereof are omitted
30 as appropriate for clarifying the description.
[0012]

Fig. 1 is a block diagram showing a configuration of a display control
apparatus 100 according to a first example embodiment. The display control
5
apparatus 100 includes a setting unit 101, a determination unit 102, and a first
display control unit 103. The setting unit 101 sets a parameter according to an
input of a user. The parameter is, for example, a regularization parameter in a
regression with a regularization term performed by the determination unit 102.
5 The regularization parameter is also referred to as a regularization strength.
[0013]
The determination unit 102 determines, for each of areas of a fingerprint
image obtained by dividing the fingerprint image, whether the qual ity of a ridge
pattern in the area is satisfactory or not based on the parameter set by the setting
10 unit 101. Each of the divided areas may be one pixel. The determination unit
102 determines whether the quality of the ridge pattern in the area, or in an area
at and around this area is satisfactory or not. When there is blurring or the like
in the ridge pattern, it is determined that the quality of this ridge pattern is low.
In the case where each of the divided areas is one pixel, the determination uni t
15 102 may determine whether the quality of the ridge pattern in an area composed
of several pixels at and around the pixel of interest is satisfactory or not.
[0014]
For example, the determination unit 102 performs a regression with
regularization based on the regularization parameter set by the setting unit 101,
20 and performs fitting for the ridge pattern using a plurality of template images.
Then, the determination unit 102 may determine whether the quality of the ridge
pattern is satisfactory or not according to the result of the fitting.
[0015]
The first display control unit 103 makes (e.g., instructs) a display unit
25 displays the fingerprint image according to the result of the determination. The
display unit is a display device such as a display. Th e first display control unit
103 may, for example, generate a display image in which a poor-quality area is
colored a predetermined background color, and make the display unit display the
generated display image.
30 [0016]
Fig. 2 is a flowchart showing a flow of a display control method according
to the first example embodiment. Firstly, the setting unit 101 sets a parameter
according to an input of a user (Step S101). Next, the determination unit 102
determines, for each area, whether the quality of the ri dge pattern is satisfactory
6
or not based on the parameter set in the step S101 (Step S102). Lastly, the first
display control unit 103 makes (e.g., instructs) the display unit display the
fingerprint image according to the result of the determination made in the step
S102 (Step S103).
5 [0017]
As described previously, in the related art, it has not been possible to
appropriately classify areas in a fingerprint image into normal areas and defective
areas. In contrast to this, according to this example embod iment, a user can
check a display image and then set an appropriate parameter, so that it is possible
10 to appropriately classify areas in a fingerprint image.
[0018]
Note that the display control apparatus 100 includes a processor, a
memory, and a storage device (not shown). Further, a computer program in
which processes of a display control method according to this example
15 embodiment are implemented is stored in the storage device. Further, the
processor loads the computer program from the storage device into the memory
and executes the loaded computer program. In this way, the processor
implements the functions of the setting unit 101, the determination unit 102, and
the first display control unit 103.
20 [0019]
Alternatively, each of the setting unit 101, the determination unit 102, and
the first display control unit 103 may be implemented by dedicated hardware.
Alternatively, some or all of the components of each apparatus may be
implemented by general-purpose or dedicated circuitry, a processor, or a
25 combination thereof. These components may be implemented by using a single
chip or may be implemented by using a plurality of chips connected through a
bus. Some or all of the components of each apparatus may be implemented by a
combination of the above-described circuitry or the like and the program.
Further, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an
30 FPGA (Field-Programmable Gate Array), or the like can be used as the processor.
[0020]
Further, in the case where some or all of the components of the display
control apparatus 100 are implemented by a plurality of information processing
apparatuses, circuitry, or the like, the plurality of information processing
7
apparatuses, circuitry, or the like may be disposed in one place in a concentrated
manner or in a plurality of places in a distributed manner. For example, the
information processing apparatus, circuitry, or the like may be implemented in a
form in which the components or the like are connected through a communication
5 network, i.e., may be implemented as a client-server system, a cloud computing
system, or the like. Further, the functions of the display control apparatus 100
may be provided in the form of SaaS (Software as a Service).
[0021]

10 Fig. 3 is a block diagram showing a configuration of a display control
apparatus 100a according to a second example embodiment. The display control
apparatus 100a includes a storage unit 110, a control unit 120, a memory 130, a
display unit 140, and an input unit 150.
[0022]
15 The storage unit 110 is a storage device such as a hard disk drive or a
flash memory. The control unit 120 controls each of the functions of the display
control apparatus 100a. The memory 130 is a volatile storage device such as a
RAM (Random Access Memory), and is a storage area for temporarily holding
information during the operation of the control unit 120. The display unit 140 is
20 an interface connected to a display device such as a display. The input unit 150
is an input interface connected to an input device such as a mouse or a keyboard.
[0023]
The storage unit 110 stores at least a display control program 111 and
templates 112. The display control program 111 is a computer program in which
25 a display control method according to this example embodiment is implemented.
The templates 112 are emphasized images obtained by extracting stripe patterns
from a fingerprint image. The templates 112 may be, for example, emphasized
images obtained by performing filtering processes on a fingerprint image by using
Gabor filters.
30 [0024]
The templates 112 may include a plurality of types of template images in
which widths (pitches) of ridges are different from one template image to another,
and may include a plurality of types of template images in which directions of
ridges are different from one template image to another. The templates 112 may
8
include, for example, 24 types of template images, i.e., six types of template
images in which directions of ridges are different from one types of template
images to another, and each of which (i.e., each of the six types) includes four
types of template images in which pitches of ridges are different from one
5 template image to another.
[0025]
A method of generating template images by performing filtering processes
will be described hereinafter. Fig. 4 collectively shows 24 types of Gabor filters
in one image. By performing filtering processes on a fingerprint image using 24
10 types Gabor filters, 24 types of emphasized images are obtained.
[0026]
Six types of filters, which are horizontally arranged, indicated by a symbol
A1 have the same pitch as each other and directions different from each other.
The same applies to filterers indicated by symbols A2, A3 and A4. The pitches
15 of the filter groups A1 to A4 differ from each other. Note that six types of
filters included in the filter group A4 are referred to as filters A41 to A46,
respectively. The filters A41 to A46 have the same pitch as each there, but have
directions different from each other. Further, the pitches of the filters A41 to
A46 are different from those of the filterers included in the filter groups A1 to
20 A3.
[0027]
Fig. 5 is an example of a fingerprint image. As an example, Fig. 6 shows
a result of a case where the filter A44 is applied to this fingerprint image. By
applying the filter A44 to the fingerprint image, a predetermined pitch and a
25 horizontal component are extracted from the fingerprint image. The image
shown in Fig. 6 is an example of a template image included in the templates 112.
That is, by performing filtering processes on a fingerprint image by using the 24
types of filters shown in Fig. 4, it is possible to generate 24 types of template
images from the fingerprint image.
30 [0028]
Note that Fig. 7 is an image that is obtained by combining emphasized
images each of which is obtained by applying a respective one of the filters A41
to A46 to a fingerprint image. It is possible to reproduce the fingerprint image
by combining the emphasized images. As will be describ ed later, a
9
determination unit 122 of the control unit 120 can determine the quality of each
area from the number of template images that have been required to reproduce the
ridge pattern.
[0029]
5 The control unit 120 will be described by referring to Fig. 3 again. The
control unit 120 loads the display control program 111 from the storage unit 110
into the memory 130 and executes the loaded display control program 111. In
this way, the control unit 120 implements the functions of a setting unit 121, a
determination unit 122, a first display control unit 123, and a second display
10 control unit 124. Note that the setting unit 121 is an example of the setting unit
101, the determination unit 122 is an example of the determination unit 102.
Further, the first display control unit 123 is an example of the first display
control unit 103.
[0030]
15 The setting unit 121 sets a parameter according to an input from the input
unit 150. The parameter is used when the determination unit 122 calculates, for
each area, an evaluation value representing the quality of the area. The input
may be an operation performed for a slider bar displayed by the second display
control unit 124 (which will be described later). The determination unit 122
20 determines, for each of areas obtained by dividing the fingerprint image, whether
the quality of the ridge pattern in the area is satisfactory or not based on the
above-described parameter. For example, the determination unit 122 may
determine, for each pixel, whether the quality of the pixel is satisfactory or not.
[0031]
25 The determination unit 122 performs a regression with a regularization
term based on a regularization parameter set by the setting unit 121. The
regression with a regularization term is, for example, a Lasso regression. Note
that the determination unit 122 performs fitting for the ridge pattern by using a
plurality of template images. That is, the determination unit 122 reproduces the
30 ridge pattern as a linear sum of a plurality of template images. In other words, it
can be said that the determination unit 122 optimizes a regression coefficient.
Then, the determination unit 122 determines whether the quality of the ridge
pattern is satisfactory or not according to the result of the above -described fitting.
[0032]
10
For example, the determination unit 122 can determine the quality of the
ridge pattern based on the number of template images for which, as the result of
the fitting, the regression coefficient is any value other than zero. In other
words, the determination unit 122 calculates an evaluation value based on the
5 number of template images that are required to reproduce the ridge pattern, and
then can determine the quality of the ridge pattern according to the evaluation
value.
[0033]
It is considered that when the quality of the ridge pattern in each area is
10 high, the direction, the line thickness, and the like of the ridge pattern are
constant. In such a case, the ridge pattern can be reproduced by using a small
number of template images. On the other hand, a ridge pattern in a low-quality
area becomes a complex stripe pattern, so that the number of templates required
to reproduce the area is large. Therefore, for example, when the number of
15 template images required to reproduce the ridge pattern is equal to or greater than
a predetermined number, the determination unit 122 can determine that the quality
of the area is defective (i.e., poor or unsatisfactory).
[0034]
The result of the fitting performed by the determination unit 122 also
20 changes according to the regularization parameter set by the setting unit 121.
When the regularization parameter is increased, the number of template images
required to reproduce the ridge pattern increases, so that the number of areas of
which the quality is determined to be defective increases. Conversely, when the
setting unit 121 decreases the regularization parameter, the number of areas of
25 which the quality is determined to be defective decreases.
[0035]
The first display control unit 123 makes (e.g., instructs) the display unit
140 display the fingerprint image according to the result of the determination by
the determination unit 122. For example, the first display control unit 123 may
30 generate a display image in which pixels in a poor-quality area are colored a
predetermined background color, and makes the display unit 140 display the
generated display image.
[0036]
Figs. 8, 9 and 10 show examples of display images displayed by the first
11
display control unit 123. Fig. 8 shows a display image in the case where th e
regularization parameter is the smallest among those of the display images shown
in Figs. 8 to 10. In Fig. 8, the area of which the quality is determined to be
defective (i.e., poor or unsatisfactory) is small, and for example, an image of a
5 low-quality area, indicated by a symbol B1, is also shown.
[0037]
Fig. 9 shows a display image when the regularization parameter is
increased from that in Fig. 8. The area of which the quality is determined to be
defective (i.e., poor or unsatisfactory) is increased from that in Fig. 8, and the
10 defective area in the box indicated by the symbol B1 shown in Fig. 8 is colored
the background color. Fig. 10 shows a display image when the regularization
parameter is further increased from that in Fig. 9. The area of whi ch the quality
is determined to be defective (i.e., poor or unsatisfactory) is increased from that
in Fig. 9, and most of the area in the fingerprint image is colored the background
15 color.
[0038]
Fig. 11 shows an example of a display screen (i.e., a displ ayed window)
C0 that the display control apparatus 100a makes (e. g., instructs) the display unit
140 display. The first display control unit 123 makes the display unit 140
20 display a display image C2 according to the result of the determination by the
determination unit 122. In Fig. 11, the image shown in Fig. 9 is displayed as the
image C2. The first display control unit 123 may display a fingerprint image C1
for which the quality determination is performed. In such a case, a user can
determine whether the setting of the regularization parameter is appropriate or not
25 by comparing the fingerprint image C1 with the original fingerprint image.
[0039]
The second display control unit 124 shown in Fig. 3 displays, for example,
a slider bar C4 and a slider C5 shown in Fig. 11. In such a case, the setting unit
121 sets the regularization parameter according to the position of the slider C5 on
30 the slider bar C4.
[0040]
When the user moves the slider C5 to the right end of the slider bar C4,
the setting unit 121 sets the regularization parameter to the maximum value. For
example, the first display control unit 123 may display the image shown in Fig.
12
10 as the display image C2.
[0041]
When the user moves the slider C5 to the left end of the slider bar C4, the
setting unit 121 sets the regularization parameter to the minimum value. For
5 example, the first display control unit 123 may display the image shown in Fig. 8
as the display image C2.
[0042]
Note that the user may input a parameter or the like by using a touch panel
or the like. In such a case, the display control apparatus 100a may change the
10 parameter according to the direction of a swiping action or the like performed by
a user's finger(s). Note that the inputting operation is not limited to the slider
operation using a mouse or the like, and also is not limited to the swiping action.
[0043]
Note that the second display control unit 124 may display an element(s)
15 such as a button(s), in addition to or in place of the slider bar, on the display unit
140. In such a case, the regularization parameter is set according to the
operation (or the action) that the user has performed on the displayed button.
[0044]
The user can select, by changing the parameter through the operation
20 performed on the slider, the touch panel, or the like, an area that is displayed
according to the quality of the area on an area -by-area basis in the fingerprint
image in a more flexible manner.
[0045]
According to this example embodiment, an operator can check the result of
25 the determination of the quality of the fingerprint image, so that he/she can
appropriately set the regularization parameter.
[0046]
Advantageous effects of this example embodiment will be described
hereinafter in detail. In a fingerprint image, there are high q uality areas and
30 low-quality areas in a mixed manner. Therefore, after corrections are made to
the low-quality areas, the corrected fingerprint image is registered in a database.
[0047]
In this process, there is a problem that if the correction process is also
applied to the high-quality areas, the quality of the fingerprint image is lowered.
13
Accordingly, it is possible to register a high-quality fingerprint image in a
database by appropriately classifying areas in the fingerprint image according to
the quality thereof.
[0048]
5 According to this example embodiment, when a user changes a parameter
used for the classification according to the quality, the result of the classification
into high quality areas and low-quality areas changes. The user can set t he
parameter to an appropriate value by checking the displayed image. Further,
since the low-quality areas are not shown in the display image, there is no need to
10 erase a part(s) of the fingerprint (i.e., a part(s) of the ridges) shown in a defective
area(s) in the correction process.
[0049]
Note that although the above-described example embodiments have been
described as hardware configurations, the present disclosure is not limited to the
15 hardware configurations. The present disclosure may also be implemented by
causing a CPU to execute a computer program.
[0050]
In the above-described examples, the program can be stored and provided
to a computer using any type of non-transitory computer readable media. Non20 transitory computer readable media include any type of tangible storage media.
Examples of non-transitory computer readable media include magnetic storage
media (floppy disks, magnetic tapes, hard disk drives), optical magnetic storage
media (e.g., magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CDR/W, DVD (Digital Versatile Disc), and semiconductor memories (e.g., mask
25 ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, and
RAM (Random Access Memory)). Further, the program may be provided to a
computer using any type of transitory computer readable media. Examples of
transitory computer readable media include electric signals, optical signals, and
electromagnetic waves. Transitory computer readable media can provide the
30 program to a computer via a wired communication li ne (e.g., electric wires, and
optical fibers) or a wireless communication line.
Reference Signs List
[0051]
14
100, 100a DISPLAY CONTROL APPARATUS
101, 121 SETTING UNIT
102, 122 DETERMINATION UNIT
103, 123 FIRST DISPLAY CONTROL SETTING UNIT
5 124 SECOND DISPLAY CONTROL UNIT
110 STORAGE UNIT
111 DISPLAY CONTROL PROGRAM
112 TEMPLATE
130 MEMORY
10 140 DISPLAY UNIT
150 INPUT UNIT
15
WE CLAIM:
1. A display control apparatus comprising:
setting means for setting a parameter according to an input of a user;
5 determination means for determining, for each of areas of a fingerprint
image obtained by dividing the fingerprint image, whether quality of a ridge
pattern in the area is satisfactory or not based on the parameter; and
first display control means for making display means display the
fingerprint image according to a result of the determination.
10
2. The display control apparatus according to Claim 1, wherein
the setting means sets a regularization parameter in a regression with
regularization according to the input, and
the determination means performs fitting for the ridge pattern by using a
15 plurality of template images by the regression with regularization based on the
regularization parameter, and determines whether the quality of the ridge pattern
is satisfactory or not according to a result of the fitting.
3. The display control apparatus according to Claim 2, wherein the
20 regression with regularization is a Lasso regression.
4. The display control apparatus according to Claim 2 or 3, wherein the
template images are emphasized images obtained by applying filters capable of
extracting stripe patterns to the fingerprint image.
25
5. The display control apparatus according to any one of Claims 1 to 4,
further comprising second display control means for displ aying a slider bar on the
display means, wherein
the setting means sets the parameter according to a position of a slider on
30 the slider bar.
6. A display control method comprising:
setting, by a computer, a parameter according to an input of a user;
determining, by the computer, for each of areas of a fingerprint image
16
obtained by dividing the fingerprint image, whether quality of a ridge pattern in
the area is satisfactory or not based on the parameter; and
making, by the computer, display means display the fingerprint image
according to a result of the determination.
5
7. The display control method according to Claim 6, wherein
a regularization parameter is set in a regression with regularization
according to the input, and
fitting for the ridge pattern is performed by using a plurality of template
10 images by the regression with regularization based on the regularization
parameter, and it is determined whether the quality of the ridge pattern is
satisfactory or not according to a result of the fittin g.
8. A non-transitory computer readable medium storing a display control
15 program for causing a computer to perform:
a process for setting a parameter according to an input of a user;
a process for determining, for each of areas of a fingerprint image
obtained by dividing the fingerprint image, whether quality of a ridge pattern in
the area is satisfactory or not based on the parameter; and
20 a process for making display means display the fingerprint image
according to a result of the determination.