Image analysis – Applications – Personnel identification
Reexamination Certificate
2002-12-26
2004-05-04
Johns, Andrew W. (Department: 2621)
Image analysis
Applications
Personnel identification
Reexamination Certificate
active
06731780
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. P2001-392748, filed on Dec. 25, 2001; the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fingerprint image judgment apparatus which judges whether or not fingerprint image data is correctly read and to program thereof.
2. Description of the Related Art
A conventional fingerprint image judgment apparatus
10
will be described with reference to
FIGS. 1
to
5
.
FIG. 1
is a hardware configuration view of the conventional fingerprint image judgment apparatus
10
.
The conventional fingerprint image judgment apparatus
10
reads a fingerprint image as digital data (fingerprint image data) by use of a fingerprint sensor
15
, and outputs the fingerprint image data, which is judged to have been correctly read, to an external device (not shown) by means of a data output unit
16
. “Fingerprint image data” is composed of a plurality of pixel values.
As shown in
FIG. 1
, the conventional fingerprint image judgment apparatus
10
includes a CPU
11
, a storage device
12
, a control memory
13
, a data memory
14
, the fingerprint sensor
15
and the data output unit
16
.
The CPU
11
is a central processing unit for interpreting and executing a fingerprint image judgment program
12
1
stored in the storage device
12
. The storage device
12
is a unit for storing the fingerprint image judgment program
12
1
.
The control memory
13
and the data memory
14
are where the various data is temporarily stored in order for the CPU
11
to execute the fingerprint image judgment program
12
1
. The entire fingerprint image data read by use of the fingerprint sensor
15
is stored temporarily in the data memory
14
. In the case of using the fingerprint sensor
15
that reads fingerprint image data of, for example, 256 pixels in the X-axis direction and 256 pixels in the Y-axis direction, a data memory
14
having a memory size equivalent to 64 KB (256×256=64K) is necessary. Herein, contrast information (pixel values) related to a fingerprint image of one pixel is expressed by one byte. Moreover, the pixel value is expressed by a value in a range of “0” to “255”. When the fingerprint image of one pixel is “black”, the pixel value is “0”. Meanwhile, when the fingerprint image of one pixel is “white”, the pixel value is “255”.
The fingerprint sensor
15
is a device that reads the fingerprint image as the digital data (fingerprint image data) for every line in the X-axis direction (or Y-axis direction) and stores the read fingerprint image data in the data memory
14
.
FIG. 2
shows a state whereby the fingerprint sensor
15
reads the fingerprint image data for every line in the Y-axis direction and stores the read fingerprint image data (a plurality of pixel values) in the data memory
14
.
In
FIG. 2
, the fingerprint sensor
15
reads a pixel value at a coordinate position of (X, Y)=(n, i) and stores the read pixel value at an address position of V_r [n, i] in the data memory
14
.
In
FIG. 2
, since the fingerprint sensor
15
that reads fingerprint image data (a plurality of pixel values) of X
max
pixels in the X-axis direction and Y
max
pixels in the Y-axis direction is used, the data memory
14
having a memory size of (X
max
×Y
max
) bytes or more is used.
The data output unit
16
is a unit that outputs the fingerprint image data to the external device (not shown). The fingerprint image data is the data judged to have been correctly read by the fingerprint image judgment program
12
1
executed by the CPU
11
.
FIGS. 3
to
5
are flowcharts illustrating an operation for judging, by the fingerprint image judgment program
12
1
, whether or not the fingerprint image data has been correctly read.
In step
701
, the fingerprint sensor
15
stores all pixel values of the read fingerprint image data at the predetermined address position V_r [n, i] of the data memory
14
. Herein, a variable “n” is a value in a range of 1 to X
max
, and a variable “i” is a value in a range of 1 to Y
max
.
In step
702
, the fingerprint image judgment program
12
1
counts the number of ridges in the fingerprint image along all the lines in the Y-axis direction, and substitutes the number for the variable “Y
n
”. In step
703
, the fingerprint image judgment program
12
1
counts the number of ridges in the fingerprint image along all the lines in the X-axis direction, and substitutes the number for the variable “X
i
”.
In step
704
, the fingerprint image judgment program
12
1
judges whether or not the values of the variables “Y
n
” and “X
i
” are values in the predetermined range.
Specifically, when the values of the variables “Y
n
” and “X
i
” are in the predetermined range, the fingerprint image data is judged to have been correctly read by the fingerprint sensor
15
(normal end).
On the other hand, when the values of the variables “Y
n
” and “X
i
” are not in the predetermined range, the fingerprint image data is judged not to have been correctly read by the fingerprint sensor
15
(abnormal end).
In
FIG. 4
, a description will be made in detail for the operation (step
702
) in which the fingerprint image judgment program
12
1
counts the number of ridges in the fingerprint image along all the lines in the Y-axis direction and substitutes the number for the variable Y
n
”.
In step
801
, the fingerprint image judgment program
12
1
substitutes the value “0” for the variables “n”, “i” and “Y
n
” (initialization). In step
802
, the fingerprint image judgment program
12
1
increases the value of the variable “n” by only “1”. In step
803
, the fingerprint image judgment program
12
1
increases the value of the variable “i” by only “1”.
In step
804
, the fingerprint image judgment program
12
1
judges whether or not the pixel at the address position V_r [n, i] of the data memory
14
forms a ridge in the Y-axis direction. For example, a threshold value indicating a boundary between a ridge and a valley has been set previously. When the pixel value at the address position V_r [n,i−1] is equal to or more than the threshold value and the pixel value at the address position V_r [n, i] is less than the threshold value, the fingerprint image judgment program
12
1
judges that the pixel at the address position V_r [n, i] forms a ridge in the Y-axis direction.
When it is judged that the pixel at the address position V_r [n, i] of the data memory
14
forms a ridge in the Y-axis direction (YES), the process advances to step
805
. Meanwhile, it is judged that the pixel at the address position V_r [n, i] of the data memory
14
does not form a ridge in the Y-axis direction (NO), the process advances to step
806
.
In step
805
, the fingerprint image judgment program
12
1
increases the value of the variable “Y
n
” by 1. In step
806
, the fingerprint image judgment program
12
1
judges whether or not the variable “i” is equal to or more than the value “Y
max
”.
When the variable “i” is equal to or more than the value “Y
max
”, the fingerprint image judgment program
12
1
judges that the count of the number of ridges for the n
th
line in the Y-axis direction is finished, and the process advances to step
807
.
Meanwhile, when the variable “i” is less than the value “Y
max
”, the fingerprint image judgment program
12
1
judges that the count of the number of ridges for the n
th
line in the Y-axis direction is not finished, and the operations from step
803
to step
805
are repeated for the n
th
line in the Y-axis direction.
In step
807
, the fingerprint image judgment program
12
1
judges whether or not the variable “n” is equal to or more than the value “X
max
”.
When the variable “n” is equal to or more than the value “X
max
”(YES) in step
807
, the fingerprint image judgment program
12
1
judges that the count of the
Iizuka Miyuki
Kobayashi Kazuo
Tsuji Hiroyuki
Holmes Brenda O.
Johns Andrew W.
Kilpatrick & Stockton LLP
NTT Electronics Corporation
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