U.S. patent application number 09/730677 was filed with the patent office on 2002-06-06 for method and apparatus to select the best video frame to transmit to a remote station for cctv based residential security monitoring.
This patent application is currently assigned to Philips Electronics North America Corporation. Invention is credited to Cohen-Solal, Eric, Colmenarez, Antonio JR., Gutta, Srinivas, Lyons, Damian M..
Application Number | 20020067258 09/730677 |
Document ID | / |
Family ID | 24936357 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020067258 |
Kind Code |
A1 |
Lyons, Damian M. ; et
al. |
June 6, 2002 |
METHOD AND APPARATUS TO SELECT THE BEST VIDEO FRAME TO TRANSMIT TO
A REMOTE STATION FOR CCTV BASED RESIDENTIAL SECURITY MONITORING
Abstract
A security monitoring system including: an alarm system having
detectors for detection of an alarm in a structure; at least one
camera for capturing image data inside and/or outside the
structure; a processor for selecting a subset of the image data
upon the occurrence of the alarm based on a predetermined criteria;
and a modem for transmitting the subset of image data to a remote
location. Preferably, the at least one camera is a video camera,
the image data is video image data, and the subset of the image
data is at least one video frame of the video image data.
Preferably, the processor ranks each video frame from the image
data according to how well each video frame meets the predetermined
criteria and the modem transmits a predetermined number of video
frames having the best rank to the remote location. Preferably, the
predetermined criteria is selected from a group consisting of: how
centered a difference region is in the video frame; how large the
difference region is; whether the difference region consists of a
large difference region or a group of smaller difference regions;
the contrast of the difference region; the lighting condition on
the difference region; whether a face is detected in the
difference; whether the video frame is blurred; how much skin color
is contained in the video frame; if a person is recognized in the
video frame; and the lighting condition on a region of motion in
the video frame.
Inventors: |
Lyons, Damian M.; (Putnam
Valley, NY) ; Cohen-Solal, Eric; (Ossining, NY)
; Gutta, Srinivas; (Buchanan, NY) ; Colmenarez,
Antonio JR.; (Peekskill, NY) |
Correspondence
Address: |
Jack E. Haken
C/O U.S Philips Corporation
Intellectual Property Department
580 White Plains Road
Tarrytown
NY
10591
US
|
Assignee: |
Philips Electronics North America
Corporation
|
Family ID: |
24936357 |
Appl. No.: |
09/730677 |
Filed: |
December 6, 2000 |
Current U.S.
Class: |
340/541 ;
340/540; 348/E7.086 |
Current CPC
Class: |
G08B 13/19604 20130101;
G06V 40/161 20220101; G08B 13/19602 20130101; H04N 7/181 20130101;
G08B 13/19669 20130101 |
Class at
Publication: |
340/541 ;
340/540 |
International
Class: |
G08B 013/00 |
Claims
What is claimed is:
1. A security monitoring system comprising: an alarm system having
means for detection of an alarm in a structure; at least one camera
for capturing image data inside and/or outside the structure; a
processor for selecting a subset of the image data upon the
occurrence of the alarm based on a set of predetermined criteria;
and transmission means for transmitting the subset of image data to
a remote location.
2. The security monitoring system of claim 1, wherein the at least
one camera is a video camera, the image data is video image data,
and the subset of the image data is at least one video frame of the
video image data.
3. The security monitoring system of claim 1, wherein the processor
is a computer vision system for analyzing the image data according
to the predetermined criteria.
4. The security monitoring system of claim 3, further comprising an
image recording system for recording the image data to be analyzed
by the computer vision system.
5. The security monitoring system of claim 4, wherein the image
data is recorded for a predetermined time period before and after
the occurrence of the alarm.
6. The security monitoring system of claim 4, wherein the image
data is analog image data, the system further comprising an analog
to digital converter for converting the analog image data to
digital image data prior to being analyzed by the computer vision
system.
7. The security monitoring system of claim 1, further comprising a
compression means for compressing the subset of the image data
prior to transmission to the remote location.
8. The security monitoring system of claim 1, wherein the
transmission means is a modem for transmitting the subset of image
data to a remote location over a data link operatively connected to
the modem and the remote location.
9. The security monitoring system of claim 1, wherein the at least
one camera is a video camera, the image data is video image data,
and the subset of the image data is at least one video frame of the
video image data, wherein the processor ranks each video frame from
the image data according to how well each video frame meets the
predetermined criteria and the transmission means transmits a
predetermined number of video frames having the best rank to the
remote location.
10. The security monitoring system of claim 1, wherein the at least
one camera is a video camera, the image data is video image data,
and the subset of the image data is at least one video frame of the
video image data, wherein the processor subtracts an established
background from each video frame resulting in a difference region,
and wherein the predetermined criteria are selected from a group
consisting of: how centered the difference region is in the video
frame; how large the difference region is in the video frame;
whether the difference region consists of a large difference region
or a group of smaller difference regions in the video frame; the
contrast of the difference region in the video frame; the lighting
condition on the difference region in the video frame; and whether
a face is detected in the difference region in the video frame.
11. The security monitoring system of claim 10, wherein if the set
of predetermined criteria includes whether a face is detected in
the difference region of the video frame, a further set of
predetermined criteria is selected from a group consisting of: how
much of the face is visible in the video frame; whether the face is
turned towards or away from the video frame; and whether key
features of the face are visible in the video frame.
12. The security monitoring system of claim 1, wherein the at least
one camera is a video camera, the image data is video image data,
and the subset of the image data is at least one video frame of the
video image data, and wherein the predetermined criteria are
selected from a group consisting of: whether the video frame is
blurred; how much skin color is contained in the video frame; if a
person is recognized in the video frame; and the lighting condition
on a region of motion in the video frame.
13. A method for monitoring a structure, the method comprising the
steps of: detecting an alarm in the structure; capturing image data
inside and/or outside the structure; selecting a subset of the
image data upon the occurrence of the alarm based on a set of
predetermined criteria; and transmitting the subset of image data
to a remote location.
14. The method of claim 13, further comprising the step of
recording the image data.
15. The method of claim 14, wherein the recording step comprises
recording the image data for a predetermined time period before and
after the occurrence of the alarm.
16. The method of claim 14, wherein the image data is analog image
data, the method further comprising the step of converting the
analog image data to digital image data.
17. The method of claim 13, further comprising the step of
compressing the subset of the image data prior to transmission to
the remote location.
18. The method of claim 13, wherein the image data is video image
data and the subset of the image data is at least one video frame
of the video image data, wherein the method further comprises the
step of ranking each video frame from the image data according to
how well each video frame meets the predetermined criteria and the
transmission means transmits a predetermined number of video frames
having the best rank to the remote location.
19. The method of claim 13, wherein the image data is video image
data and the subset of the image data is at least one video frame
of the video image data, wherein the method further comprises the
step of subtracting an established background from each video frame
resulting in a difference region, and wherein the predetermined
criteria are selected from a group consisting of: how centered the
difference region is in the video frame; how large the difference
region is in the video frame; whether the difference region
consists of a large difference region or a group of smaller
difference regions in the video frame; the contrast of the
difference region in the video frame; the lighting condition on the
difference region in the video frame; and whether a face is
detected in the difference region in the video frame.
20. The method of claim 19, wherein if the predetermined criteria
includes whether a face is detected in the difference region of the
video frame, a further set of predetermined criteria are selected
from a group consisting of: how much of the face is visible in the
video frame; whether the face is turned towards of away from the
video frame; and whether key features of the face are visible in
the video frame.
21. The method of claim 1, wherein the image data is video image
data and the subset of the image data is at least one video frame
of the video image data, and wherein the set of predetermined
criteria are selected from a group consisting of: whether the video
frame is blurred; how much skin color is contained in the video
frame; if a person is recognized in the video frame; and the
lighting condition on a region of motion in the video frame.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to security
monitoring systems and, more particularly, to a security monitoring
system in which a video frame from video surveillance cameras is
selected for transmission to a remote monitoring station based on a
set of predetermined criteria.
[0003] 2. Prior Art
[0004] Security monitoring systems of the prior art, particularly
residential security systems, typically utilize a box that monitors
contact sensors for doors and windows and one or more infra-red
sensors for area monitoring. When a contact is triggered or an
infra-red sensor triggers, an alarm is sounded and a signal is sent
via a data link such as a phone line to a central monitoring site.
The central monitoring site typically initiates a set of phone
calls, to the homeowner, to work, and/or to a designated neighbor
to determine if the alarm signal was due to an unauthorized
intruder or just to an accidental triggering by a family member or
other authorized occupant of the structure.
[0005] If the alarm signal cannot be resolved by the phone calls,
it is passed to the local police department. According to the
International Association of Chiefs of Police (www.theiacp.org),
alarm calls comprise 10% to 30% of police calls, and 94% to 98% of
the calls turn out to be "false alarms" in the sense that they were
not due to an unauthorized intruder.
[0006] Significant portions (over 70%) of "false alarms" are caused
by what is referred to as exit/entrance conflicts. For instance, in
the situation of a residential alarm system, the homeowner or other
authorized occupant of a residence often arms the security system
while leaving the residence and shortly thereafter realizes that
they have forgotten something in the residence. As they return to
the residence, they enter without disarming the system thereby
causing an alarm to be sounded and/or an alarm signal to be sent to
a central monitoring site. Similarly, the homeowner may arm the
security system and remain inside the residence, such as during the
night and may thereafter leave to get something outside the
residence, e.g., the morning paper, thereby triggering a false
alarm.
[0007] In view of the prior art, there is a need for a security
monitoring system, which resolves these and other types of
entry/exit conflicts.
SUMMARY OF THE INVENTION
[0008] Therefore it is an object of the present invention to
provide a security monitoring system which reduces the number of
false alarms inherent in the prior art security monitoring
systems.
[0009] It is a further objective of the present invention to
provide a security monitoring system which transmits image data to
a remote monitoring station for inspection by the monitoring staff
to determine if an alarm is a true or false alarm.
[0010] It is yet another objective of the present invention to
provide a security monitoring system which selects a portion of the
image data to the remote monitoring station based upon a set of
predetermined criteria such that the bandwidth for transmitting the
image data is not exceeded.
[0011] Accordingly, a security monitoring system is provided. The
security monitoring system comprises: an alarm system having means
for detection of an alarm in a structure; at least one camera for
capturing image data inside and/or outside the structure; a
processor for selecting a subset of the image data upon the
occurrence of the alarm based on a set of predetermined criteria;
and transmission means for transmitting the subset of image data to
a remote location.
[0012] Preferably, the at least one camera is a video camera, the
image data is video image data, and the subset of the image data is
at least one video frame of the video image data. The transmitted
image data should be such as to allow a monitoring operator to
quickly decide if the alarm is a true alarm or a false alarm. More
preferably, the processor ranks each video frame from the image
data according to how well each video frame meets a set of
predetermined criteria which evaluate how useful they are to a
monitoring operator in distinguishing false/true alarms, and the
transmission means transmits a predetermined number of video frames
having the best rank to the remote location.
[0013] One approach to transmitting image data to the remote
location is to simply transmit the frame at the time of the alarm,
or a set of frames corresponding to some time interval around the
alarm time (e.g., transmit an image taken 0.5 seconds before the
alarm, at the alarm and 0.5 seconds after the alarm). However, such
a scheme is not guaranteed to catch the cause of the alarm, and
even if the cause is caught, it may not be portrayed in a form
quickly interpretable by the monitoring operator (e.g., the image
may catch the heel of an intruder departing through a doorway).
[0014] In preferred implementations of the security monitoring
system of the present invention, the processor subtracts an
established background from each video frame resulting in a
difference region. The predetermined criteria that evaluate how
useful the image is to a monitoring operator are selected from a
group consisting of: how centered the difference region is in the
video frame; how large the difference region is in the video frame;
whether the difference region consists of a large difference region
or a group of smaller difference regions in the video frame; the
contrast of the difference region in the video frame; the lighting
condition on the difference region in the video frame; and whether
a face is detected in the difference region in the video frame. If
the predetermined criteria includes whether a face is detected in
the difference region of the video frame, further predetermined
criteria are preferably selected from a group consisting of: how
much of the face is visible in the video frame; whether the face is
turned towards of away from the video frame; and whether key
features of the face are visible in the video frame.
[0015] In alternative implementations of the security monitoring
system of the present invention, the predetermined criteria are
selected from a group consisting of: whether the video frame is
blurred; how much skin color is contained in the video frame; if a
person is recognized in the video frame; and the lighting condition
on a region of motion in the video frame.
[0016] In yet another preferred implementation of the security
monitoring of the present invention, the system further comprises:
an image recording system for recording the image data to be
analyzed by the computer vision system wherein the image data is
recorded for a predetermined time period before and after the
occurrence of the alarm; an analog to digital converter for
converting analog image data to digital image data prior to being
analyzed by the processor; and a compression means for compressing
the subset of the image data prior to transmission to the remote
location.
[0017] Also provided are methods for security monitoring of a
structure having the security monitoring system of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These and other features, aspects, and advantages of the
apparatus and methods of the present invention will become better
understood with regard to the following description, appended
claims, and accompanying drawings where:
[0019] FIG. 1 illustrates a schematical view of a structure having
the security monitoring system of the present invention.
[0020] FIG. 2 illustrates a flow chart outlining a preferred method
for utilizing the system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Although this invention is applicable to numerous and
various types of security monitoring systems and image data, it has
been found particularly useful in the environment of residential
security monitoring systems and video image data. Therefore,
without limiting the applicability of the invention to residential
security monitoring systems and video image data, the invention
will be described in such environment.
[0022] Referring now to FIG. 1, there is illustrated a preferred
implementation of a security monitoring system of the present
invention, referred to generally by reference numeral 100. The
security monitoring system comprises an alarm system 102 having
means for detecting an unauthorized individual in a structure 104.
Such means can be any conventional detectors known in the art, such
as magnetic door contacts 106 for detecting the opening of an
entrance door 108 or an infrared motion detector 110 appropriately
positioned to detect the presence of an unauthorized intruder.
Those skilled in the art will recognize that any such type of
conventional detectors may be used without departing from the scope
or spirit of the present invention.
[0023] If the alarm system 102 is triggered an alarm is sounded
and/or an alarm signal is transmitted to a remote monitoring
station 112 or a local police station (hereinafter both are
referred to as a "remote monitoring station"). As discussed above,
many of the alarms turn out to be false alarms in that the
triggering of the alarm was unintentional or by an individual who
is authorized to be in the structure 104 (e.g., a family member or
maid of a residence). The problem with false alarms can be resolved
by augmenting the alarm system 102 with at least one camera 114,
and preferably, with a set of inexpensive cameras, such as CCTV
video cameras 114, 116 for capturing image data of individuals
inside and/or outside the structure 104. For those cameras 114, 116
placed in a room 118 of the structure 104, the cameras 114, 116 are
preferably placed high in the room 118 and positioned to have as
complete a view as possible. For entrance ways 120 it is advisable
not to have the camera 114 pointed right at the door 108 unless the
camera 114 is equipped with a backlight filter (not shown).
[0024] The alarm system 1O2 is further augmented with means for
storing the image data captured by the cameras, such as an image
recording system 122 and means to transmit the image data 102a to a
remote monitoring station, which is preferably a built-in function
of the alarm system 102. It is preferred that the image recording
system 122 is preferably a computer or other processor having a
storage device such as a hard drive and an image capture card.
However, those skilled in the art will recognize that the image
recording system 122 can be of any type known in the art without
departing from the scope and spirit of the present invention.
[0025] Furthermore, a compression means 124 can also be provided to
compress the video image data prior to transmission to the remote
monitoring station 112. Such compression and transmission means are
well known in the art and a detailed description thereof is omitted
for the sake of brevity. Compression means 124 can include encoders
which compress data according to a standard compression algorithm,
such as JPEG (for image data) and MPEG (for video data).
Transmission means 102a can include any device such as a modem
which transmits data via a data link 126 such as a telephone, ISDN,
or coaxial cable line. Upon receipt of the image data, the staff of
the remote monitoring station 112 can literally "see" what caused
the alarm and can even perform a comparison of an individual who
caused the alarm with the individuals authorized to be in the
structure 104, as is described in co-pending U.S. Patent
Application No. ______ (Docket No. 701609, 13933) which is
incorporated herein by its reference.
[0026] However, given the limitations on transmission bandwidth,
particularly from a residence which typically uses a telephone
(POTS) connection, it is practical to only send a few video frames
from the video image data to the remote monitoring station 112. The
system 100 of the present invention selects a portion of the image
data captured by the camera(s) 114, 116 that is more representative
of the cause of the alarm being triggered, thereby filtering out
image data that is not or may not be conclusive as to the
determination at hand, namely, if the alarm is a true or false
alarm. Since, the remote monitoring station 112 uses the
transmitted image data to make its decision, the selection of what
images to transmit is crucial. The transmitted image data should be
such as to allow a monitoring operator to quickly decide if the
alarm is a true alarm or a false alarm. In the case of video image
data, the portion thereof to transmit to the remote monitoring site
is one or more video frames from the video image data.
[0027] To make the selection of what video frame(s) to transmit,
the system 100 of the present invention first digitizes the video
image data (if not already digitized) in an analog to digital (A/D)
converter 128 and feeds the digitized video image data to a
processor 130, which can be or include a computer vision system
132. The processor 130 analyzes the digitized video image data and
decides what portion (i.e., video frames) to transmit based on a
set of predetermined criteria. Of course, the set of predetermined
criteria can comprise of a single criteria. If the alarm system 102
has several monitoring zones, with one or more cameras per zone,
the criterion to be used can simply be to compress and transmit the
image data from the zone that triggered the alarm. Similarly, if a
video motion detection scheme is used, then only the video image
data from cameras that trigger a motion detection alarm is
compressed and transmitted to the remote monitoring station
112.
[0028] A more sophisticated set of criteria can include using an
established background subtraction technique to eliminate parts of
the video frames from previous video frames that represent a
background scene leaving a set of regions which has changed from
the background scene. There are many approaches known in the art to
do this, such as that disclosed in A. Elgammal et al.,
Non-Parametric Model for Background Subtraction, presented at Int.
Conf. Computer Vision & Pattern Recognition, Workshop on
Motion, Fort Collins Colo., June 1999.
[0029] Background subtraction provides as output a set of regions
of the video frame that contain potential intruder images. Some
simple approaches can be taken to rank whether a specific video
frame from a video camera contains an intruder image of sufficient
quality/content to send to the central monitoring station 112. For
example, the more centered (in the video frame) the regions
detected by background subtraction, the better framed the image
shows the intruder, and the better the video frame rates for
sending to a monitoring station. Other criteria for rating a video
frame in addition to centeredness include, whether one large region
versus a set of smaller regions is reported, whether the region
shows good contrast, or whether the region is large versus
small.
[0030] Similarly, face detection can be applied to the region with
the use of the computer vision system 132. Such computer vision
systems and algorithms are well known in the art, such as that
disclosed in H. Rowley et al., Human Face Detection in Visual
Scenes, Advances in Neural Information Processing Systems 8, 1996,
pp. 875-881 and H. Rowley et al., Rotation Invariant Neural
Network-Based Face Detection, Proceedings of IEEE Conference on
Computer Vision and Pattern Recognition, June, 1998. Briefly, such
computer vision systems 132 look for skin color among the pixels of
the image data (since skin color has a distinctive hue). If a
grouping of skin color pixels is above a threshold (i.e., 20% of
the image data), the computer vision system concludes that the
grouping may be a face. If other criteria are met for the grouping,
such as having an elliptical shape and regions which appear to be
facial features (e.g., two eyes, a nose, and a mouth), the computer
vision system concludes that the grouping of pixels is the face of
the unauthorized individual. The more visible the face the better
the image ranks. More visible can mean: how much of the face is
seen (the more the better), whether the face is turned towards or
away, and whether key features such as eyes are visible.
[0031] The computer vision system 132 can be used for other image
processing techniques to decide which video image data is to be
transmitted to the remote monitoring station 112. Such techniques
can use the following criteria to select the portion of the video
image data to be transmitted to the remote monitoring station, the
video frame which is least blurred, the video frame that contains
the most skin color information, the video frame that has the best
lighting condition on the region of motion or difference, the video
frame in which the presence of a person is recognized, etc.
[0032] Preferably, a specific time limit is set up around the time
of the alarm, for example, a predetermined time before (t1 seconds)
and after (t2 seconds) the alarm is triggered. All the video image
data from the camera(s) 114, 116 in this time period (t1..t2) are
analyzed and given a rank based on a set of predetermined criteria
which may include any one or more of the above discussed criteria.
The top scoring n video frames are sent to the central monitoring
station, where n can be any number. Preferably n=1, i.e., a single
video frame is compressed and transmitted to the remote monitoring
station 112.
[0033] The methods of the present invention which utilize the
preferred implementation of the security monitoring system
illustrated in FIG. 1 will now be briefly described with reference
to FIG. 2. The method of FIG. 2 being generally referred to by
reference numeral 200. At step 202, an alarm is triggered in a
structure 104, such as a residence. The alarm is detected by any
conventional means known in the art, such as by detectors 106, 110
operatively connected to alarm system 102. At step 204, the image
data, preferably video image data, captured by cameras 114, 116 is
recorded by the image recording system 122 for a preferred period
of t1 to t2, t1 being a period in seconds just prior to the
triggering of the alarm and t2 being a period in seconds after the
triggering of the alarm.
[0034] At step 206, the video image data recorded for the period
from t1 to t2 is digitized by the A/D converter 128 and supplied to
a processor 130, which may be or include a computer vision system
132. At step 208, the digitized video image data is analyzed by the
processor 130 and/or computer vision system 132 according to a set
of predetermined criteria, such as any one or more of the criteria
discussed above. At step 210, each video frame in the digitized
video image data is ranked according to how well it meets the
predetermined criteria. At step 212, a predetermined number n of
video frames having the best ranking are preferably compressed by
the compression means 124 prior to being transmitted by the
transmitting means 102a to the remote monitoring station 112. As
discussed above, n is preferably 1.
[0035] Those skilled in the art will appreciate that the system and
methods of the present invention provide the ability to filter out
false alarms by transmitting the most useful image from a set of
CCTV cameras to a remote monitoring station where the monitoring
staff (or local police) can inspect it and make a decision on
whether or not the alarm is false.
[0036] While there has been shown and described what is considered
to be preferred embodiments of the invention, it will, of course,
be understood that various modifications and changes in form or
detail could readily be made without departing from the spirit of
the invention. It is therefore intended that the invention be not
limited to the exact forms described and illustrated, but should be
constructed to cover all modifications that may fall within the
scope of the appended claims.
* * * * *