CCTV Lighting Basics: Things I’ve Learned.
Wed, 01/07/2009 - 16:22 — Erron - 6 comments
The subject of lighting is often overlooked while designing or installing CCTV systems. Perhaps this is because we are unsure what, or if, there is anything we can do about it. My experience however, has been that there are many simple things we can do during the design or install that can make a big difference, and in fact there are some cases where it makes more sense to change or adjust the lighting rather than the camera itself.
The basics of proper lighting are actually rather straightforward and are the same as what you learned in your high-school photography class.
Here’s my Top 5 Tips for CCTV Lighting:
TIP 1 - Get a Good Position – Always try to position the camera with the light source behind the camera. This allows the light to bounce off the face of subject and into the lens of your camera giving you maximum detail of your scene. This of course is easy to do indoors but a little more complicated outdoors where the lighting changes as the sun rises and sets. Try to figure out or watch where the shadows fall during the day and where the lights shine at night to find a suitable ’best case’ location for the camera.
TIP 2 – Watch your Back(lighting) – Backlighting issues occur when light you cannot control, such as the sun coming through the windows, light up the back of an object more than the front. You are left with dark shadowed objects or areas of the room you cannot see. While many cameras have compensation that can help, you can also make the situation better through both camera placement and even leaving the room lights on during the day. To fully utilize the backlighting compensation feature of standard cameras, it is important to try to keep the brightest spots near the center of the cameras field-of-view. This is where many cameras sample the room light level. This does not apply to dynamic range cameras which break down the field-of-view into smaller sections and sample (and adjust) each section independently.
TIP 3 – Time for Reflection – There is no doubt that more lighting will typically always help any situation, but too much lighting can cause glare and reflections which can be bothersome. If you do add lighting in a closed environment and find you have glare, try doing what you did in photography class which is to reflect the light off a nearby surface like a white wall. This will not only reduce glare but will also reflect light towards your target at multiple angles which increases contrast of the image giving a better overall picture. This can be important to help distinguish things like distance and the true color of a person’s clothing or a vehicle.
TIP 4 – Keeping it Light – Today there are many different types of lighting such as incandescent, mercury halide, mercury vapor, sodium vapor, florescent, neon, argon, xenon, LED, and the list goes on and on. Each type of lighting produces more light in certain areas of the lighting spectrum, and less in others. To the human eye it all looks like light, but cameras have a different range of sensitivity than our eyes. In fact, some cameras such as black & white are highly sensitive to infrared, while others such as most color cameras, barely see it. What this means is that for your lighting (or your camera) to be most effective you might need to select a camera that is sensitive to the lighting you have at the location. In most cases this is not an issue with today’s technology, but for those situations where you need to make the best of the lighting you have, this can be an important factor. The best way to deal with this is to find out what types of lights are in use. You can often get this information from the maintenance staff. Once you have this information, talk with your camera manufacturer and they can recommend a camera best suited for that particular light source. There have been instances where we actually recommended that the facility upgrade to a more efficient bulb type, which also produced more of the correct light for their camera system. In this case it was a win-win situation, but of course this is not always possible.
TIP 5 – A Shot in the Dark – Infrared lighting is the new buzz word that seems to have captivated the market. Infrared illuminators are built into many cameras these days, and are offered as a way to allow cameras to see in the dark without adding additional lighting. This is often used for covert situations. One of the main problems we see with infrared however is that it creates very little contrast and often times will make everything look washed out. This of course leads to disappointment and a less than quality installation. What many people should consider however is that infra-red can be used in conjunction with traditional lighting to achieve a well lit scene without creating contrast problems found in IR only installations. This can also be useful in areas where aesthetics are important and too much conventional light would be distasteful.
Certainly there are many more things to consider when dealing with lighting issues, but hopefully these 5 tips can help you deal with the most often overlooked and most impactful issues that we face.
Comments
Lighting affects on IP systems
Erron, great post. A sometimes overlooked aspect of lighting is how it can affect IP systems. Changes in lighting to a tuned IP system affects the performance and behavior of the system. For example, encoding and compression performance changes as the lighting changes. Likewise network physics. Application performance and behavior post-encoding can also be affected, such as motion detection and video analytics.
As you say, outdoor conditions are always challenging. So customers should measure performance and behavior of the system under both day/night conditions and attempt to find a good compromise. They should be cognizant of indoor lighting conditions and either accommodate changing light or attempt to control them based on the performance and behavior they require from their head-end system.
When troubleshooting an IP system, adding the question "what were the lighting conditions?" to the checklist can often save a lot of time as well.
Steve Mitchell
Pelco
Good Topic - What about WDR?
Great post Erron!
Another thing to consider in camera selection is using a Wide Dynamic Camera that uses the Pixim chip technology.
A good WDR camera can take even the most difficult lighting situations and produce a much higher quality picture than the typical CCD camera will.
As you know they are espeicially good in situations with high contrast and in changing light conditions. A ccd camera has limited ability to adjust with changing light compared to a Pixim WDR camera.
Keep up the good postings!!!
Peter Brissette
GSP America
peter@gspamerica.com
www.gspamerica.com
How about analytics?
With analytics being the craze these days, what do you feel is the affect of lighting conditions for analytics. For example, if a face camera is pointed at a perimeter door, an analog camera cannot compensate for the narrow field of view required to capture faces. With a person walking through the door, the subject stays in the FoV no more than 5 seconds.
The SDIII technology from Panasonic requires 10 seconds to adjust to a flood of light and this is some of the best BLC technology around. What then? IP? Manufacturers like Axis don't even compare to analog in terms of BLC. Thoughts?
Re: How about analytics?
I think Erron’s tips are a great start and make a fundamental point which is that we need to stop thinking about just the camera as being the entire potential solution and that some simple tips can help 90% of the time.
As for your specific example, it’s completely valid and may take more than just camera technology alone to solve and certainly depends on the actual environment.
Lighting the newer technologies
Lighting, as photographers have known for years, is crucial to a quality image from any camera. In the security world we cannot always control lighting therefore we must find ways to adapt to lighting conditions. We are all familiar with Back Lighting Control (BLC), Auto Iris (AI) lenses, Automatic Gain Control (AGC) and Color to Black and white switching or Day/Night cameras. How about the new technologies like Digital Slow Shutter (DSS), Digital Noise Reduction (DNR) elsewhere branded as 'Intensifier' and even Wide Dynamic Range (WDR)? With all of these technology choices we have new and sometimes confusing options when buying and setting up a camera. I'd like to see more discussion along these lines.
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