U.S. patent application number 11/113263 was filed with the patent office on 2006-07-20 for vehicle monitoring method, specific character pattern recognition device, and vehicle monitoring system.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Hajime Kanno.
Application Number | 20060157012 11/113263 |
Document ID | / |
Family ID | 36682561 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060157012 |
Kind Code |
A1 |
Kanno; Hajime |
July 20, 2006 |
Vehicle monitoring method, specific character pattern recognition
device, and vehicle monitoring system
Abstract
In a vehicle monitoring method, recognition processing of a
specific character pattern of a vehicle is performed by extracting
a specific character pattern area from a taken image data. When the
specific character pattern cannot be recognized, a compression
range is judged as being a vehicle area clipped from the taken
image data, and image data of the clipped area is compressed at a
low compression ratio. When the specific character pattern is
partially recognized, the compression range is judged as being the
specific character pattern area clipped from the taken image data,
and image data of the clipped area is compressed at the low
compression ratio. When the specific character pattern is fully
recognized, the compression range is judged as being the specific
character pattern area clipped from the taken image data, and image
data of the clipped area is compressed at a high compression
ratio.
Inventors: |
Kanno; Hajime; (Kawasaki,
JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
36682561 |
Appl. No.: |
11/113263 |
Filed: |
April 25, 2005 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
G08G 1/0104
20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2005 |
JP |
2005-012376 |
Claims
1. A vehicle monitoring method comprising the steps of: performing
recognition processing of a specific character pattern of a vehicle
by extracting a specific character pattern area from a taken image
data in order to monitor the vehicle based on a recognized
character pattern; determining, when a result of the recognition
processing indicates that the specific character pattern cannot be
recognized, a compression range as being a vehicle area clipped
from the taken image data, wherein image data of the clipped area
is compressed at a predetermined low compression ratio to store or
transmit the compressed image data; determining, when the result
indicates that the specific character pattern is partially
recognized, the compression range as being the specific character
pattern area clipped from the taken image data, wherein image data
of the clipped area is compressed at the low compression ratio to
store or transmit the compressed image data; and determining, when
the result indicates that the specific character pattern is fully
recognized, the compression range as being the specific character
pattern area from the taken image data, wherein image data of the
clipped area is compressed at a predetermined high compression
ratio to store or transmit the compressed image data.
2. A specific character pattern recognition device comprising: a
recognition processing unit having a frame memory, a character
recognition processing unit and an image processing unit, the frame
memory temporarily storing an image data of a vehicle taken by an
image-taking unit, the character recognition processing unit
performing recognition processing of a specific character pattern
of the vehicle, and the image processing unit clipping a vehicle
area containing the whole vehicle from the taken image data and
clipping a specific character pattern area from the vehicle area; a
compression range/ratio judging unit judging a compression range
and a compression ratio based on a result of the recognition
processing wherein, when the result of the recognition processing
indicates that the specific character pattern cannot be recognized,
the compression range and the compression ratio are judged as being
the vehicle area and a predetermined low compression ratio, when
the result indicates that the specific character pattern is
partially recognized, the compression range and the compression
ratio are judged as being the specific character pattern area and
the low compression ratio, and when the result indicates that the
specific character pattern is fully recognized, the compression
range and the compression ratio are judged as being the specific
character pattern area and a predetermined high compression ratio;
an image compression unit which is responsive to a judgment result
of the compression range/ratio judging unit, the image compression
unit clipping a corresponding area of image data for the
compression range from the taken image data of the frame memory,
and performing compression processing of the image data of the
clipped area at the compression ratio; and a transmitting/receiving
unit transmitting the compressed image data from the image
compression unit.
3. The specific character pattern recognition device according to
claim 2 further comprising a data storing unit storing the
compressed image data provided by the image compression unit,
together with the result of the recognition processing of the
specific character pattern of the vehicle.
4. The specific character pattern recognition device according to
claim 3 further comprising a matching processing unit performing
matching processing between an externally requested vehicle
specific character pattern and the result of the recognition
processing stored in the data storing unit, and, when a match
occurs as a result of the matching processing, the compressed image
data is read from the data storing unit and transmitted.
5. A vehicle monitoring system including a plurality of specific
character pattern recognition devices and a center which are
connected through a communication line, each specific character
pattern recognition device comprising: a recognition processing
unit performing recognition processing of a specific character
pattern of a vehicle based on a taken image data, and the
recognition processing unit clipping a vehicle area containing the
whole vehicle from the taken image data, and clipping a specific
character pattern area from the vehicle area; a compression
range/ratio judging unit judging a compression range and a
compression ratio based on a result of the recognition processing
wherein, when the result of the recognition processing indicates
that the specific character pattern cannot be recognized, the
compression range and the compression ratio are judged as being the
vehicle area and a predetermined low compression ratio, when the
result indicates that the specific character pattern is partially
recognized, the compression range and the compression ratio are
judged as being the specific character pattern area and the low
compression ratio, and when the result indicates that the specific
character pattern is fully recognized, the compression range and
the compression ratio are judged as being the specific character
pattern area and a predetermined high compression ratio; an image
compression unit which is responsive to a judgment result of the
compression range/ratio judging unit, the image compression unit
clipping a corresponding area of image data for the compression
range from the taken image data, and performing compression
processing of the image data of the clipped area at the compression
ratio; and a transmitting/receiving unit transmitting the
compressed image data from the image compression unit, and the
center comprising: a data management table in which the compressed
image data received from each specific character pattern
recognition device through the communication line are stored; and a
display unit displaying the compressed image data.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority of Japanese Patent Application No. 2005-012376, filed on
Jan. 20, 2005, the entire contents of which are herein incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to the vehicle monitoring
method, the specific character pattern recognition device, and the
vehicle monitoring system in which the specific character pattern
of a vehicle is recognized and monitored.
[0004] 2. Description of the Related Art
[0005] Specific character patterns are given to various kinds of
vehicles respectively such that the patterns may not overlap.
Therefore, performing automatic reading of the specific character
pattern to recognize the specific character pattern of the vehicle
is possible.
[0006] There have been proposed various kinds of systems that are
applicable to the automation of charge payment of the tollgates on
the toll roads, the judgment of whether the parking vehicles of the
parking lot are the contractors' own, and the detection of burglar
vehicles or the like. In such systems, the image signal indicating
the image of the vehicle specific character pattern has to be
processed. It is demanded for such systems to carry out the image
processing of the image signal efficiently.
[0007] FIG. 7 shows the composition of the conventional vehicle
monitoring device.
[0008] In the vehicle monitoring device of FIG. 7, the vehicle
detecting unit 70 detects that the passing vehicle arrives at the
image-taking position, and outputs the detection signal to the
recognition processing unit 72. The recognition processing unit 72
outputs the image-taking instruction to the image-taking unit 71 to
take the image of the passing vehicle. The image-taking unit 71
takes the image of the vehicle according to the image-taking
instruction, and transmits the resulting image signal to both the
recognition processing unit 72 and the image transmission unit
74.
[0009] The recognition processing unit 72 extracts the specific
character pattern area from the taken image of the vehicle, and
recognizes the vehicle specific character pattern based on the
characters or numbers included in the specific character pattern
area. As for the recognition processing of the vehicle specific
character pattern, there are known various kinds of means, such as
means for clipping of one character, means for pattern matching of
the clipped character, and means for matching through the feature
extraction.
[0010] The vehicle monitoring device of FIG. 7 is configured so
that, only when the passing vehicle passes through the image-taking
position, the image-taking unit 71 takes the image of the passing
vehicle.
[0011] Moreover, the vehicle specific character patterns are
registered beforehand in the matching unit 73. The vehicle specific
character pattern which is recognized by the recognition processing
unit 72 is transmitted to the matching unit 73, and the matching
unit 73 performs matching of the received vehicle specific
character pattern with the recorded vehicle specific character
patterns. And the matching unit 73 transmits the result of the
matching to the recognition processing unit 72.
[0012] If the signal indicating the matching coincidence is
received from the matching unit 73, the recognition processing unit
72 transmits the matched vehicle specific character pattern to the
image transmission unit 74. The image transmission unit 74
transmits the vehicle specific character pattern and the taken
image signal to the image recording/displaying unit 75. The image
recording/displaying unit 75 adds the date information and the
image-taking position information to the received pattern/image
information and records the resulting information. In the image
recording/displaying unit 75, the recorded information is searched
and read out based on the information related to the vehicle
specific character pattern, the date, the image-taking position,
etc., when the necessity occurs. The read-out information is
displayed on the monitor of the image recording/displaying unit 75,
which enables the checking of the vehicle of concern by viewing the
monitor. See Japanese Laid-Open Patent Application No.
09-282590.
[0013] Moreover, there is known another vehicle monitoring method
(see Japanese Laid-Open Patent Application No. 09-261620). In this
method, the vehicle specific character pattern on the specific
character pattern is recognized based on the taken image signal,
compression processing of the taken image signal is performed, and
the recognized vehicle specific character pattern is added to the
compressed image signal so that the resulting image information is
recorded. The compressed image signal of the recorded information
is read out based on the vehicle specific character pattern, and
expansion processing (decompression processing) of the read
compressed image signal is performed so that the expanded image is
displayed on the monitor.
[0014] Moreover, there is known another vehicle monitoring device
(see Japanese Laid-Open Patent Application No. 09-037232). In this
device, a remote monitoring unit is provided in which one
monitoring range is selected from among a plurality of monitoring
ranges, the compression ratio of the image signal and the
transmission time are changed corresponding to the selected
monitoring range, and the transmission of the compressed image
signal is performed.
[0015] For example, when the monitored object is moving at high
speed in the selected monitoring range, the compression ratio is
made high and the transmission of the image signal is performed at
high speed in order to allow the monitoring screen to follow the
change of the monitored object during the high-speed movement. When
the monitored object is moving at low speed in the selected
monitoring range, the compression ratio is made low and the
transmission of the image signal is performed at low speed in order
to make the resolution of the monitoring screen high, increasing
the quality of the image being displayed.
[0016] As mentioned above, the image of the vehicle specific
character pattern is taken, the specific character pattern is
extracted from the taken image signal through the image processing,
and the character recognition processing is performed, so that
vehicle monitoring can be carried out based on the recognized
character pattern.
[0017] However, the image-taking conditions are greatly different
depending on the angle of attachment of the specific character
pattern, the state of the dirt in the specific character pattern,
and the weather condition. Therefore, in the case of a poor weather
condition, it is difficult to recognize the specific character
pattern through the image processing.
[0018] In the case where the recognition processing of the specific
character pattern of the vehicle is difficult to perform, an
improved recognition processing unit can be adopted to recognize
the vehicle specific character pattern. In the improved recognition
processing unit, the taken image signal is inputted to the display
unit and the image of the vehicle is displayed on the display
monitor. The area of the specific character pattern in the image of
the vehicle can be identified by viewing the image on the display
monitor.
[0019] However, when the display monitor is installed at a position
that is distant from the installation position of the image
transmission unit 74 as shown in FIG. 7, it is necessary to
transmit the image data from the image transmission unit 74 to the
monitor through the telephone line. Even if the compression
processing of the image data is carried out, there is much amount
of image data contained in one screen of the image, and the use of
high-speed transmission path is required. Therefore, it has been
difficult to carry out the vehicle monitoring remotely by
connecting the center and the distributed image processing units
through the existing communication network of low bit rate.
SUMMARY OF THE INVENTION
[0020] An object of the present invention is to provide an improved
vehicle monitoring method in which the above-mentioned problems are
eliminated.
[0021] Another object of the present invention is to provide a
vehicle monitoring method in which the compression range and
compression ratio for the compression processing of the taken image
signal are controlled in response to the result of recognition
processing of the specific character pattern of the vehicle in
order to reduce the amount of the transmission data.
[0022] In order to achieve the above-mentioned objects, the present
invention provides a vehicle monitoring method comprising the steps
of: performing recognition processing of a specific character
pattern of a vehicle by extracting a specific character pattern
area from a taken image data in order to monitor the vehicle based
on a recognized character pattern; setting, when a result of the
recognition processing indicates that the specific character
pattern cannot be recognized, a compression range to a vehicle area
containing the whole vehicle, clipped from the taken image data,
wherein image data of the clipped area is compressed at a
predetermined low compression ratio to store or transmit the
compressed image data; setting, when the result indicates that the
specific character pattern is partially recognized, the compression
range to the specific character pattern area clipped from the taken
image data, wherein image data of the clipped area is compressed at
the low compression ratio to store or transmit the compressed image
data; and setting, when the result indicates that the specific
character pattern is fully recognized, the compression range to the
specific character pattern area clipped from the taken image data,
wherein image data of the clipped area is compressed at a
predetermined high compression ratio to store or transmit the
compressed image data.
[0023] According to the present invention, when the vehicle
specific character pattern is fully recognized, the compressed
image data in which the image of the vehicle specific character
pattern having the comparatively small area is compressed at the
high compression ratio can be transmitted. It is possible to easily
transmit the compressed image data through the communication
network of low bit rate.
[0024] Moreover, in order to achieve the above-mentioned objects,
the present invention provides a specific character pattern
recognition device comprising: a recognition processing unit having
a frame memory, a character recognition processing unit and an
image processing unit, the frame memory temporarily storing an
image data of a vehicle taken by an image-taking unit, the
character recognition processing unit performing recognition
processing of a specific character pattern of the vehicle, and the
image processing unit clipping a vehicle area containing the whole
vehicle from the taken image data and clipping a specific character
pattern area from the vehicle area; a compression range/ratio
judging unit judging a compression range and a compression ratio
based on a result of the recognition processing wherein, when the
result of the recognition processing indicates that the specific
character pattern cannot be recognized, the compression range and
the compression ratio are judged as being the vehicle area and a
predetermined low compression ratio, when the result indicates that
the specific character pattern is partially recognized, the
compression range and the compression ratio are judged as being the
specific character pattern area and the low compression ratio, and
when the result indicates that the specific character pattern is
fully recognized, the compression range and the compression ratio
are judged as being the specific character pattern area and a
predetermined high compression ratio; an image compression unit
which is responsive to a judgment result of the compression
range/ratio judging unit, the image compression unit clipping a
corresponding area of image data for the compression range from the
taken image data of the frame memory, and performing compression
processing of the image data of the clipped area at the compression
ratio; and a transmitting/receiving unit transmitting the
compressed image data from the image compression unit.
[0025] The above-mentioned specific character pattern recognition
device may be configured so that the specific character pattern
recognition device further comprises a data storing unit which
stores the compressed image data provided by the image compression
unit, together with the result of the recognition processing of the
specific character pattern of the vehicle.
[0026] Moreover, the above-mentioned specific character pattern
recognition device may be configured so that the specific character
pattern recognition device further comprises a matching processing
unit which performs matching processing between an externally
requested vehicle specific character pattern and the result of the
recognition processing stored in the data storing unit, and, when a
match occurs as a result of the matching processing, the compressed
image data is read from the data storing unit and transmitted.
[0027] Moreover, in order to achieve the above-mentioned objects,
the present invention provides a vehicle monitoring system which
includes a plurality of specific character pattern recognition
devices and a center which are connected through a communication
line, each specific character pattern recognition device
comprising: a recognition processing unit performing recognition
processing of a specific character pattern of a vehicle based on a
taken image data, and the recognition processing unit clipping a
vehicle area containing the whole vehicle from the taken image
data, and clipping a specific character pattern area from the
vehicle area; a compression range/ratio judging unit judging a
compression range and a compression ratio based on a result of the
recognition processing wherein, when the result of the recognition
processing indicates that the specific character pattern cannot be
recognized, the compression range and the compression ratio are
judged as being the vehicle area and a predetermined low
compression ratio, when the result indicates that the specific
character pattern is partially recognized, the compression range
and the compression ratio are judged as being the specific
character pattern area and the low compression ratio, and when the
result indicates that the specific character pattern is fully
recognized, the compression range and the compression ratio are
judged as being the specific character pattern area and a
predetermined high compression ratio; an image compression unit
which is responsive to a judgment result of the compression
range/ratio judging unit, the image compression unit clipping a
corresponding area of image data for the compression range from the
taken image data, and performing compression processing of the
image data of the clipped area at the compression ratio; and a
transmitting/receiving unit transmitting the compressed image data
from the image compression unit, and the center comprising: a data
management table in which the compressed image data received from
each specific character pattern recognition device through the
communication line are stored; and a display unit displaying the
compressed image data.
[0028] According to the present invention, the compression range
and compression ratio of the taken image data are determined in
response to the result of the automatic recognition processing of
the vehicle specific character pattern. Even when the vehicle
specific character pattern cannot be recognized, the compression
processing of the vehicle area, not the full screen, is performed,
and the amount of the transmission data can be reduced.
[0029] Moreover, the image data of the vehicle area can be
displayed at the high compression ratio on the display unit at the
center, the possibility of recognition of the vehicle specific
character pattern can be increased by viewing the image with the
high compression ratio on the display unit. Moreover, when the
vehicle specific character pattern can be recognized, the
compression processing of the specific character pattern with the
further smaller area is performed. Reducing the amount of the
transmission data further is possible, and it is possible to easily
transmit the compressed image data through the communication
network of low bit rate.
[0030] Since the ratio of recognition of the vehicle specific
character pattern is comparatively high, even when the compressed
image data is transmitted continuously, the transmission data in
many cases is the highly compressed image data of the specific
character pattern area. The amount of the transmission data, even
if it includes the data of the recognized vehicle specific
character pattern, is comparatively small. It is possible to easily
transmit the compressed image data through the communication
network of low bit rate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Other objects, features and advantages of the present
invention will be apparent from the following detailed description
when read in conjunction with the accompanying drawings.
[0032] FIG. 1 is a diagram for explaining the outline composition
of the vehicle monitoring system in the preferred embodiment of the
invention.
[0033] FIG. 2 is a block diagram showing the composition of the
vehicle monitoring system in the preferred embodiment of the
invention.
[0034] FIG. 3 is a flowchart for explaining the vehicle monitoring
method in the preferred embodiment of the invention.
[0035] FIG. 4 is a diagram for explaining the compression
range.
[0036] FIG. 5 is a block diagram showing the composition of the
vehicle monitoring system in another preferred embodiment of the
invention.
[0037] FIG. 6 is a block diagram showing the composition of the
vehicle monitoring system in another preferred embodiment of the
invention.
[0038] FIG. 7 is a block diagram showing the composition of the
conventional vehicle monitoring system.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0039] A description will now be given of the preferred embodiments
of the present invention with reference to the accompanying
drawings.
[0040] FIG. 1 shows the outline composition of the vehicle
monitoring system in the preferred embodiment of the invention.
[0041] In FIG. 1, reference numeral 1 denotes the center, 2 denotes
the control processing unit, 3 denotes the display unit, 4 denotes
the data management table, 5 denotes the switched network
(network), 6 denotes the communication line, such as the telephone
line, 7 denotes the recognition device, 8 denotes the camera, and 9
denotes the vehicle. The vehicle monitoring system shown in FIG. 1
is constituted when the connection between the center 1 and the
recognition device 7 is established through the telephone line 6
which is accommodated in the switched network 5. A plurality of
recognition devices 7 which constitute part of the vehicle
monitoring system may be distributed in the highway, the general
road or the parking lot, and each recognition device 7 can be
connected with the center 10 through the telephone line.
[0042] The camera 8 may be arranged at the position where the image
of the vehicle running on the highway or the general road is taken,
or at the position where the image of the vehicle entering or
exiting the parking lot, or the image of the vehicle under parking
is taken.
[0043] The recognition device 7 is provided with the image
processing function, the character pattern recognition processing
function, the data transmitting/receiving function, etc. The
recognition device 7 processes the taken image data from the camera
8 by using the image processing function, and extracts the specific
character pattern area of the vehicle 9 from the processed image
data. The recognition device 7 recognizes the vehicle specific
character pattern by using the character recognition processing
function. In response to the result of the recognition processing,
the recognition device 7 clips the area containing the whole
vehicle 9 or the specific character pattern area from the taken
image data and determines the compression ratio. The recognition
device 7 transmits the resulting data (or the transmission data) to
the center 1 through the telephone line 6 by using the data
transmitting/receiving function.
[0044] As shown in FIG. 1, the transmission data in this case
comprises the specific character pattern information and the
compression image data. The compression image data contains, for
example, the compression range indicating the vehicle area or the
specific character pattern area, the image quality, the compression
data length, and the compressed image data. The specific character
pattern information contains, for example, the header information,
the position information, the time information, and the vehicle
specific character pattern data with the recognition result, such
as "12345".
[0045] The control processing unit 2 of the center 1 is provided
with the data management table 4, and this data management table 4
stores the transmission data received through the telephone line 6
from the recognition device 7. As shown in FIG. 1, the data
management table 4 contains, for every item, the vehicle specific
character pattern which is partially omitted, the image data in the
compression range, the image quality, and the position/time
information.
[0046] In the data management table 4 of FIG. 1, for example,
"12345" of the specific character pattern column of the item number
1 indicates the case in which the vehicle specific character
pattern is fully recognized, the image data thereof indicates the
specific character pattern area (or the vehicle number plate
region), and the image quality thereof indicates the low level.
Namely, the compression range is set to the specific character
pattern area, and the reproduction image quality is set to the low
level since the compression ratio has been set to the high
compression ratio.
[0047] Moreover, in the data management table 4 of FIG. 1, "?" of
the specific character pattern column of the item number 3
indicates the case in which the vehicle specific character pattern
cannot be recognized, the image data thereof indicates the whole
vehicle, and the image quality thereof indicates the high level.
Namely, the compression range is set to the vehicle area, and the
reproduction image quality is set to the high level since the
compression ratio has been set to the low compression ratio.
[0048] Moreover, in the data management table 4 of FIG. 1, "12?45"
of the specific character pattern column of the item number 4
indicates the case in which the characters in the vehicle specific
character pattern are partially recognized except for the character
"?", the image data thereof indicates the specific character
pattern area, and the image quality thereof indicates the high
level. Namely, the compression range is set to the specific
character pattern area, and the reproduction image quality is set
to the high level since the compression ratio has been set to the
low compression ratio.
[0049] For example, the case in which the image data of the item
number 3 in the data management table 4 is read and displayed on
the display unit 3 under control of the control processing unit 2
is considered. In this case, the compressed image data of the
vehicle area has been created at the low compression ratio, and
such image data is decompressed and displayed. Thus, the image of
the vehicle area can be displayed at the high reproduction image
quality.
[0050] Accordingly, in this case, the specific character pattern
area is checked by viewing the display screen, and this makes it
possible to read the characters in the specific character pattern
area by viewing. In such case, the column of the specific character
pattern in the data management table 4 can be corrected to the
vehicle specific character pattern currently checked by
viewing.
[0051] In the vehicle monitoring system of the present embodiment,
the compression processing of the vehicle area only is carried out,
and the amount of the transmission data can be reduced as compared
with the case in which the compression processing of the full
screen is carried out.
[0052] Moreover, when the image data of the item number 4 in the
data management table 4 is read and displayed on the display unit 3
under control of the control processing unit 2, the image of the
specific character pattern area can be displayed at the high image
quality level. This make it possible to easily check the character
"?" which has not been recognized through the automatic recognition
processing by viewing the display screen.
[0053] In such case, the column of the specific character pattern
in the data management table 4 can also be corrected to the vehicle
specific character pattern currently checked by viewing. In the
vehicle monitoring system of the present embodiment, the
compression processing of the specific character pattern area only
is carried out, and the amount of the transmission data can be
reduced further as compared with the case in which the compression
processing of the full screen or the vehicle area is carried
out.
[0054] In the case in which the vehicle specific character pattern
is fully recognized through the automatic recognition like the item
number 1, 2 or 6 in the data management table 4, the compression
processing of the specific character pattern area is performed at
the high compression ratio (which allows the reproduction image
quality to be set to the low level), and the amount of the
transmission data can be reduced further.
[0055] In such case, when the vehicle specific character pattern
which is already recognized through the automatic recognition is
displayed on the display unit 3, checking the vehicle specific
character pattern again can be easily performed even if the
reproduction image quality is at the low level.
[0056] FIG. 2 shows the composition of the vehicle monitoring
system in the preferred embodiment of the invention.
[0057] In FIG. 2, reference numeral 10 denotes the center, 11
denotes the transmitting/receiving unit, 12 denotes the control
processing unit, 13 denotes the display unit, 14 denotes the data
management table, 20 denotes the specific character pattern
recognition device, 21 denotes the recognition processing unit, 22
denotes the frame memory, 23 denotes the compression range/ratio
judging unit, 24 denotes the image compression unit, 25 denotes the
transmitting/receiving unit, 30 denotes the image-taking unit, and
40 denotes the telephone line.
[0058] The center 10 is equivalent to the center 1 in FIG. 1, the
specific character pattern recognition device 20 is equivalent to
the recognition device 7 in FIG. 1, the image-taking unit 30 is
equivalent to the camera 8 in FIG. 1, and the telephone line 40 is
equivalent to the telephone line 6 in FIG. 1.
[0059] Moreover, the control processing unit 12 corresponds to the
control processing unit 2 in FIG. 1, the display unit 13
corresponds to the display unit 3 in FIG. 1, and the data
management table 14 is equivalent to the data management table 4 in
FIG. 1. In addition, in the composition of FIG. 2, the network 5 in
FIG. 1 is omitted for the sake of convenience of illustration.
[0060] In the vehicle monitoring system of FIG. 2, the image-taking
unit 30 continuously takes at a predetermined frame period the
image of the vehicle passing position or parking position which is
selected as the image-taking range, similar to a television camera.
Alternatively, the image-taking unit 30 may be configured so that
it takes the image of the vehicle only when the vehicle exists
within the image-taking range.
[0061] In the specific character pattern recognition device 20, the
taken image signal received from the image-taking unit 30 is
digitized by the recognition processing unit 21, and stored into
the frame memory 22 of the recognition processing unit 21.
[0062] In the case in which the image is taken continuously, the
recognition processing unit 21 can recognize the difference between
the background portion (such as the road) and the moving-vehicle
portion of the taken image by taking the difference between the
frames at the predetermined time interval. Thus, the recognition
processing unit 21 clips the vehicle area containing the vehicle,
from the taken image.
[0063] Further, the recognition processing unit 21 clips the
specific character pattern area (e.g., the vehicle number plate)
from the vehicle area, and performs the character recognition
processing to recognize the characters or numbers in the specific
character pattern area.
[0064] The compression range/ratio judging unit 23 controls the
compression range and the compression ratio in response to the
result of the recognition processing of the vehicle specific
character pattern received from the recognition processing unit
21.
[0065] As mentioned above, the compression range/ratio judging unit
23 performs the judgment about the compression range and the
compression ratio as follows. When the vehicle specific character
pattern cannot be recognized, the compression range is determined
as being the vehicle area, and the compression ratio is determined
as being the predetermined low compression ratio. Moreover, when
the vehicle specific character pattern is fully recognized, the
compression range is determined as being the specific character
pattern area, and the compression ratio is determined as being the
predetermined high compression ratio. Furthermore, when the vehicle
specific character pattern is partially recognized but the
remainder cannot be recognized, the compression range is determined
as being the specific character pattern area, and the compression
ratio is determined as being the predetermined low compression
ratio.
[0066] The image compression unit 24 performs clipping and
compression processing of the area of the image data of the frame
memory 22 according to the judgment signal from the compression
range/ratio judging unit 23. The image compression unit 24
transmits the compressed image data to the transmitting/receiving
unit 25 through the compression range/ratio judging unit 23, or
transmits the compressed image data to the transmitting/receiving
unit 25 directly. The transmitting/receiving unit 25 transmits the
compressed image data from the specific character pattern
recognition device 20 to the center 10 through the telephone line
40.
[0067] The center 10 temporarily stores in the data management
table 14 the compression image data received at the
transmitting/receiving unit 11 under control of the control
processing unit 12.
[0068] The control processing unit 12 reads the compressed image
data of the vehicle with which the vehicle specific character
pattern cannot be recognized through the automatic recognition
processing, from the data management table 14 automatically or in
response to the instructions of the operator. The compressed image
data is subjected to the expansion processing in accordance with
the compression ratio specified therein, and the expanded image
data is displayed on the display unit 13.
[0069] In this case, since the image of the vehicle area can be
displayed at the high image-quality level, it is possible to
increase the possibility that the vehicle specific character
pattern be visually recognized by viewing the display screen.
[0070] FIG. 3 is a flowchart for explaining the vehicle monitoring
method in the preferred embodiment of the invention.
[0071] As shown in FIG. 3, the taken image signal received from the
image-taking unit 30 (see FIG. 2) is digitized and stored in the
frame memory 22 (S1). The difference data (the outline of the
vehicle) between the background image data and the taken image data
is extracted (S2).
[0072] The difference data extracted at the step S2 takes the
difference between the frames at the predetermined time interval
and indicates the difference between the background portion (such
as the road) and the moving-vehicle portion of the taken image. The
vehicle area containing the vehicle is clipped from the taken image
data using the difference data (S3).
[0073] And it is determined whether the vehicle can be recognized
or not (S4). Vehicles generally have various kinds of form, but
they have the size and the form different from the pedestrian etc.
Thus, the vehicles and the other moving objects are
distinguishable.
[0074] When the vehicle cannot be recognized using the difference
data, the control is transferred to the step S1. On the other hand,
when the vehicle has been recognized, the control is transferred to
the next step S5.
[0075] In the step S5, extraction processing of the specific
character pattern area from the clipped area is performed. For
example, the histogram with respect to the horizontal direction and
the vertical direction can be created, and the area of the
rectangular specific character pattern can be extracted based on
this histogram.
[0076] Alternatively, for example, the background color of the
specific character pattern is set to white, and the generally
rectangle area where the color of the background other than the
characters is white can be extracted as the specific character
pattern area.
[0077] Next, it is determined whether the specific character
pattern has been recognized (S6). When the result at the step S6 is
affirmative, the character area is clipped and the numeric values
of the characters of the specific character pattern are determined
by the pattern matching (S7). Namely, the character recognition is
performed for the clipped character area through the pattern
matching, the feature point extraction, etc.
[0078] Next, it is determined whether all the characters in the
specific character pattern area have been recognized, or it is
determined whether the vehicle specific character pattern has been
fully recognized (S8).
[0079] When the result at the step S8 is affirmative, the image
data of the vehicle specific character pattern area (which is the
clipped area) is compressed at the high compression ratio (which is
specified as the compression ratio in this case) (S9).
[0080] When the result at the step S8 is negative (i.e., when the
vehicle specific character pattern has been recognized partially),
only the characters in the specific character pattern which have
been recognized are determined (S12). And the image data of the
vehicle specific character pattern area (which is the clipped area)
is compressed at the low compression ratio (which is specified as
the compression ratio in this case) (S13).
[0081] On the other hand, when the specific character pattern
cannot be recognized, or when the vehicle specific character
pattern has not been recognized at all, the image data of the
vehicle area (which is the clipped area) is compressed at the low
compression ratio (which is specified as the compression ratio in
this case) (S11).
[0082] Subsequently, the transmission data as shown in FIG. 1 is
created, and the compressed image data with the specific character
pattern is transmitted from the specific character pattern
recognition device 20 to the center 10 (S10).
[0083] FIG. 4 is the diagram for explaining the compression range.
In FIG. 4, (a) indicates the taken image created by the
image-taking unit 30 (see FIG. 2). For example, the image data
stored in the frame memory 22 is read out and displayed on the
display screen.
[0084] And when the extraction of the specific character pattern
cannot be performed, or when the automatic recognition of the
vehicle specific character pattern cannot be performed at all, the
vehicle area is clipped from the taken image data as shown by (b)
in FIG. 4. The image data of the vehicle area is compressed at the
low compression ratio by the image compression unit 24, allowing
the image quality to be set at the high level.
[0085] Therefore, when the compressed image data in this case is
received at the center 10, the image data is expanded and displayed
on the display unit 13. In this case, the image of the vehicle with
the high image quality level can be displayed, and the specific
character pattern area can be checked by viewing the display
screen, which increases the possibility that the vehicle specific
character pattern be recognized by viewing.
[0086] Moreover, when the vehicle specific character pattern is
partially recognized through the automatic recognition, the image
data of the specific character pattern area is compressed at the
low compression ratio.
[0087] Therefore, the specific character pattern area is clipped
from the taken image data as shown by (c) or (d) in FIG. 4, and,
when the compressed image data of the specific character pattern
area with the low compression ratio is received at the center 10,
the image data is expanded and displayed on the display unit 13. In
this case, the image of the specific character pattern area with
the high image quality level can be displayed, and the specific
character pattern area can be checked by viewing the display
screen, which increases the possibility that the vehicle specific
character pattern be fully recognized by viewing.
[0088] Next, FIG. 5 shows the composition of the vehicle monitoring
system in another preferred embodiment of the invention.
[0089] In FIG. 5, the elements which are the same as corresponding
elements in FIG. 2 are designated by the same reference numerals,
and a description thereof will be omitted.
[0090] In the specific character pattern recognition device 20 of
FIG. 5, the data storing unit 26 is provided. This data storing
unit 26 is formed by a semiconductor integrated circuit memory or a
hard disk drive unit which is provided to accumulate the image
data. The data storing unit 26 is provided to accumulate the image
data, and to accumulate the compression data of the image
compression unit 24, the recognition result of the vehicle specific
character pattern by the recognition processing unit 21, and the
judgment result of the compression range/ratio judging unit 23.
[0091] For example, the compression data are accumulated in the
data storing unit 26 in the format equivalent to the format of the
data management table 4 or the format of the transmission data
shown in FIG. 1.
[0092] And the data storing unit 26 is searched from the center 10
in accordance with the time specified by the center 10 or in
accordance with the vehicle specific character pattern specified by
the center 10. The compression data which is retrieved and
extracted is read out from the data storing unit 26. The
compression data is transmitted from the transmitting/receiving
unit 25 to the telephone line 40 in the format of the transmission
data (which is, for example, shown in FIG. 1).
[0093] Therefore, it is possible for the present embodiment that,
only when the necessity occurs in the center 10, the automatically
recognized vehicle specific character pattern and the compression
image data be collected from the specific character pattern
recognition device 20.
[0094] FIG. 6 shows the composition of the vehicle monitoring
system in another preferred embodiment of the invention.
[0095] In FIG. 6, the elements which are the same as corresponding
elements in FIG. 2 or FIG. 5 are designated by the same reference
numerals, and a description thereof will be omitted.
[0096] In the specific character pattern recognition device 20 of
FIG. 6, the matching processing unit 27 is provided. When the
vehicle specific character pattern is specified by the center 10,
the matching processing unit 27 searches the vehicle specific
character pattern stored in the data storing unit 26, and carries
out matching between the specified vehicle specific character
pattern and the recognized vehicle specific character pattern. If
the coincidence of the matching occurs, the compression image is
read from the data storing unit 26, and the transmission data in
the format shown in FIG. 1 is transmitted from the
transmitting/receiving unit 25 to the center 10 through the
telephone line 6.
[0097] The present invention is not limited to the above-described
embodiments, and variations and modifications may be made without
departing from the scope of the present invention. For example, the
camera 8 or the image-taking unit 30 may be constituted by a
digital camera, so that the image of the vehicle is taken using the
digital camera at intervals of a fixed time period. Moreover, two
frame memories 22 may be provided in order to perform the
processing of creating the difference data more easily. Moreover,
the vehicle monitoring system may be controlled to change the
compression ratio to one of the multiple stages corresponding to
the number in which the vehicle specific character pattern is
recognized.
* * * * *