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LIGHTING FOR
NETWORK CAMERAS
Color rendition
Other old style lighting tech-
nologies such as halogen and
sodium lighting have a poor
colour rendition. They produce a
dull, uneven orange/yellow glow.
This leaves CCTV cameras at a
disadvantage, as they are unable
to produce high quality, true col-
our images at night, with enough
detail to identify and recognize a
target on scene.
White-light LED technol-
ogy delivers a cool white colour
temperature which is close to the
colour of day light and which
is optimised for colour CCTV.
It allows cameras to generate
images with accurate detail and
colour even at long distances.
Thermal and IR
Thermal camera technology
should not be used instead of
IR but alongside it. Both tech-
nologies have different purposes:
Thermal to detect infrared to
identify.
For distance critical applica-
tions such as border surveillance,
port surveillance, protection of
critical infrastructure or military
projects, thermal technology is
often used to detect that a sub-
ject is present at great distances,
mitted -increasing bandwidth and
storage costs.
Compression techniques such
as H.264 work on compressing
the raw data into smaller "chunks"
to reduce bandwidth require-
ments. In simple terms compres-
sion works by replicating data
from previous frames and only the
pixels that have changed (due to
colour or movement) are transmit-
ted and updated in the live video
image.
Most security professionals
will be familiar with the noisy
"white-noise" images that cameras
produce when there is not enough
light on scene. With each pixel
changing frequently the camera
is fooled into thinking there is
constant movement throughout
the image and this prevents video
compression from working.
A fundamental benefit of
professional lighting for network
cameras results from delivering
enough light to prevent noise in
the image. In turn this provides
higher quality pictures, allows
compression techniques to work
and substantially reduces band-
width and storage requirements.
Quick start
It can be forgotten how long it
takes for many lighting systems to
switch on. This can be critical to
the security system. Metal halide
lighting can take several minutes
to fully warm up compared to
modern quick start LED lighting,
which provides an instant strike.
Quick start LED lighting can
be used as a deterrent to warn
off criminals, triggered on alarm
from devices such as PIR detec-
tors. Technology such as metal
halide illumination is simply too
slow and not suitable for high
security, lighting on demand
applications.
equal the resolution of a camera
increases as its sensitivity to light
decreases. This is due to the size
of the individual pixels on a sen-
sor (think of the pixel as a little
bucket to collect light). Consider
the two examples below:
Clearly the sensor on the right
with 16 pixels has 4 times the
resolution of the sensor on the
left with 4 pixels. But take a look
at the size of the individual pixels
on each sensor; the pixels on the
sensor on the left are much larger,
capable of collecting much more
light and are therefore able to de-
liver better performance in lower
light conditions. So, most higher
megapixel cameras require in-
creased light levels to achieve high
quality night-time performance.
Bandwidth and storage
As discussed earlier in this article,
street lighting is not enough for
high quality images at night no
matter how sensitive light the
camera is.
For users of network cameras,
if the images captured are noisy
or pixilated due to insufficient
lighting, compression is unable
to work and therefore creates a
higher amount of data to be trans-
Raytec
are world leaders in LED lighting and manufacture a complete range
of infra-red and white-light LED illuminators for CCTV and general lighting
applications. All Raytec illuminators use the latest SMT LED technology to im-
prove the performance of any security system at night, delivering high quality
images, a long 10 year life, low energy consumption, low running costs and
zero maintenance. Raytec's management team has over 40 years of experi-
ence in designing, specifying and selling lighting directly to over 60 countries,
and all Raytec products are UK designed and manufactured.
For more information about Raytec's solutions, visit: www.rayteccctv.com
As the market leader in network video,
Axis
is leading the way to a smarter,
safer, more secure world - driving the shift from analog to digital video sur-
veillance. Offering network video solutions for professional installations, Axis'
products and solutions are based on an innovative, open technology plat-
form. Axis has more than 1,000 dedicated employees in 40 locations around
the world and cooperates with partners covering 179 countries. Founded in
1984, Axis is a Sweden-based IT company listed on NASDAQ OMX Stockholm
under the ticker AXIS.
For more information about Axis' solutions, visit: www.axis.com
About the sponsors
Infrared.
Thermal.
Thermal.
based on detection of a change in
temperature. When the subject
moves into the zone covered by
the infrared illumination, unlike
thermal cameras infrared can be
used to identify intruders and pick
out details such as facial features
or clothing.
Looking at the two thermal
images above at 100 meters, we
can see that a person is present,
but we cannot tell if the person
is a man or a woman or identify
any facial features. Now looking
at the IR image on the left, we
can clearly see that the person is
a young/middle aged white male,
wearing jeans and a casual jacket.
Infrared illuminators, which
throw IR light onto a scene and
can be viewed with monochrome
or day/night cameras, should not
be confused with thermal imaging
which detect infrared radiation
(heat) and create images based on
differences in surface temperature
producing false colours from these
temperatures to create an artificial
image.
Conclusion
If you are considering lighting
for your network camera system,
then this article outlines some of
the key challenges that you may
face when designing and installing
your CCTV system, and provides
top hints and tips for achieving
the best night time performance.
Every scenario is different, so it's
always advantageous to trial your
system before deciding on the final
configuration. n