Network camera experts – Axis, and CCTV lighting specialists – Raytec, held a series of test nights throughout the dark winter months of 2011 and 2012. The test nights were designed to help all security professionals tackle some of the most common practical issues when using lighting in conjunction with network cameras to achieve high performance CCTV images at night.
So what were the most useful lessons learnt during the sessions? Here’s a brief summary:
Before you set your cameras rolling, it is vital that you have correctly mounted and aligned not just your cameras but your illumination too, for the best possible CCTV performance at night.
The reality is that most cameras need a certain level of lighting to produce an effective image at night. Even the most advanced cameras require dedicated lighting to produce images with the ability to detect, identify or recognise people or objects in the scene.
It is critical to have the right angle of illumination, matched to the camera field of view. A narrow light on a wide angle can produce a bright spot on the screen and wide angle illumination on a narrow scene results in light wastage and reduced performance.
Consider the running and maintenance costs of your system.Many installations utilise multiple 300W or 500W illuminations. These can be replaced with as little as 40W of long life, cool running infrared or white-light LED illumination.
Not only does LED lighting have an inherently low power consumption, but it also lasts a lot longer - typically around 10 years and requires zero maintenance – compared to a halogen light which can last as little as 5 months. Over this ten year period, there are significant savings to be made on energy consumption, running costs, and labour.
Often, users of security systems may consider street lighting to be a good enough solution to fully illuminate a scene for capturing CCTV images at night. The user may be cautious about adding additional visible illumination on scene because of light pollution concerns. For this scenario, infrared illumination which is invisible to the human eye can be a very effective solution.
The test nights proved that high performance, low light camera technology such as the Axis Lightfinder, requires as little as 1 or 2 lux of effectively directed, colour corrected White-Light illumination. Many traditional ‘visible’ lighting solutions aim for high lux levels on the scene – this is not always required and it can often result in reduced image quality, excessive light pollution and excessive energy consumption. NB: Typical lux levels for CCTV are between 3 and 7 lux.
However, much higher megapixel cameras do require more light to achieve high quality images at night. There is one simple rule to remember, if all other variables stay 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 sensor (think of the pixel as a little bucket to collect light).
Street lighting is not enough for high quality images at night - no matter how light sensitive 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 transmitted - increasing bandwidth and storage costs.
The test nights revealed that the high performance cameras reacted very quickly to the quick start RAYLUX White-Light LED illumination. The detail was very impressive and the reaction of the cameras were instant, meaning that they can make it possible for light to be used as both a deterrent and a CCTV tool to capture accurate colour images.
Thermal camera technology should not be used instead of IR – but alongside it. Both technologies have different purposes: Thermal to detect – infrared to identify.
These points are only a brief synopsis, please click here to read the entire whitepaper including images and illustrations.