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New Technology for Security Cameras
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Video
cameras are being installed in many new applications. Nanny-cams, police and home security
networks, traffic jam monitors, and small-business webcams are just a few of
the video monitoring devices employed by and for the average American.
A report
from "Research and Markets" says that the global closed circuit
television (CCTV) market grew at a compound annual growth rate (CAGR) of 24.3%
in 2007 and is forecast to grow at a CAGR of approximately 23% from 2008 to
2012.
Systems
are available for the "do-it-yourself" type. Systems that can be installed with wireless
transmission of the video signal help in this regard. More sophisticated systems may require the
utilization of a professional installation.
Classifications of CCTV Technologies
There
are three types of CCTV technologies.
The oldest technology units are analog systems. These systems have the lowest cost for the
hardware, and are useful for some services.
The second type of CCTV is called hybrid
technology. These systems capture the
image with analog cameras, and convert the signals to digital format, which can
be more economical if it is necessary to retain long periods of video. By digitizing the data, software manipulation
of the image becomes possible.
The
newest player in security cameras is the IP camera. This camera technology can be implemented
anywhere where a computer network is available.
Because the interface cables may be avoided, this solution can result in
the lowest cost and quickest installation.
This type of interface is also best when the distance between camera and
host is significant.
Night Vision (Infrared)
Night vision
cameras are becoming more common, probably because of the publicity generated
by military night-vision systems. There
are two types of night vision cameras: those that can capture an image with
little light (most military systems are in this classification), and those that
have infrared lamps (most often IR LEDs). The distance that can be seen by this
type of IR camera is proportionate to the output of IR light.
While in
infrared mode, an infrared camera will record only in black and white, but there
are cameras available that can monitor with color during daylight hours.
Sensors on the camera automatically switch from color recording to black and
white according to the light level.
Avoid using an infrared camera that is contained in a glass or acrylic
front outdoor housing. Infrared light will reflect off the housing, creating
glare that obscures the image.
Integration of Video Security with Existing Systems
Data
storage is always a significant problem with CCTV. Video surveillance systems can be memory hogs
(For example, video with resolution of 640 x 480 at 30 frames per second and
I420 pixel format requires 640 x 480 x 30 x 1.5 = 13 MB data per second). For this reason, most systems include signal
compression to reduce the required capacity.
Even with signal compression, it will be necessary to decide on the
period of data retention, and sample rate.
Video
analytics is the technology of applying software techniques to the
interpretation of the video image, so that a computer can filter the data, and
call attention to a human operator if necessary. It is important to understand the current
limitations of this technology. One
should not expect that a CCTV system incorporating video analytics will
replicate human perception. Video images
of busy environments can be very difficult to interpret for a computer, but
images that are more static can be more successfully measured. What video analytics can do is act as a
“force multiplier”, allowing a single human to effectively monitor many cameras.
Security
cameras provide us with an additional layer of security, and as the technology
improves, this layer will continue to grow in popularity and importance.