Camera corner: Security in black and white
December 10, 2019 By Colin Bodbyl
Over recent years we have seen infrared light (or IR) become almost standard in all outdoor cameras.
Even manufacturers who shunned the idea initially and marketed against it ultimately adopted the technology. While it is effective in many applications, the percentage of cameras with built-in IR far exceeds the number of installations that really require it.
IR is a wavelength of light that is not visible to the human eye but can be captured by a camera’s image sensor. It is an inexpensive and effective way to improve image quality where no other lighting exists, but it has several trade-offs.
The most obvious shortcoming of IR is that it can only be captured in monochrome (or black and white) images. This results in the loss of sometimes critical information, like the colour of a suspect’s vehicle or the details of a person’s outfit. This can make it difficult to use the footage as evidence, given key identifying features are lost.
From an intruder’s perspective, IR is invisible. There is no question that IR lighting has no value as a deterrent when compared to traditional white lights and while humans cannot see IR, many insects can. Even insects that cannot see IR are attracted to the lights due to the warmth created by them. This can result in spider webs and flying insects blocking the camera and crippling its effectiveness.
Not all IR is the same either. Depending on the camera, built-in IR could be effective hundreds of feet away while in another camera it could be limited to 30 feet. This is an important consideration for integrators using IR cameras. After the camera has been installed, integrators need to monitor the nighttime images and ensure the IR is adjusted appropriately to suit the scene, which sometime means turning the IR off.
There have also been significant improvements in image sensor technology over recent years, allowing cameras to stay in colour mode even when available white light is minimal. Rather than defaulting to use IR after sunset, integrators must test the various settings on the camera to determine if it is necessary. In many cases they will find the camera’s colour mode is perfectly adequate throughout the night.
Image analysis technology like video analytics can also be affected by the contrast or colours in an image. In some cases, video analytics or AI may work better on a monochrome image where contrast is high. In other cases, the technology may be critically dependent on identifying features like colour in order to properly categorize or differentiate between objects.
IR is not all bad of course. In cases where there is no visible light at all, built-in IR can mean the difference between a usable image at night and a completely black screen. Using a camera in colour mode during the night can also cause a lot of noise in the image. This can increase file sizes and ultimately impact recording times. In this example, using IR and monochrome mode could improve storage times and reduce bandwidth consumption.
Before IR lighting was included in most cameras, there was a saying: “criminals bring their own light.” This is often true, but not an effective strategy. Lighting in general is still the most critical external factor affecting camera performance. Integrators and end users who understand how to manage it effectively will ultimately maximize the performance of their surveillance systems. IR is always better than nothing, but just because a camera has IR does not mean you always have to use it.
Colin Bodbyl is the chief technology officer of Stealth Monitoring (www.stealthmonitoring.com)
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