Designing Video Systems for Difficult Lighting Conditions
Technologies and time-tested tactics combine to take much of the frustration out of designing and installing video systems in difficult lighting conditions.
Challenging lighting conditions may be the biggest obstacle video system designers and installers encounter. After all, you can’t alter the laws of physics. And those laws dictate that you need light to get an image. Without light, there’s no picture. But light alone isn’t enough. The wrong kind of light, whether it is too little, too much or poorly located, such as a very bright backlight, does no good. It can even make the situation worse.
“Every camera needs light to see, but it’s the quantity and distribution of light that governs the quality of nighttime CCTV images,” says Kristin Seguin-Cory, national sales manager - U.S. and Canada, for Ottawa, Ontario-based CCTV lighting manufacturer Raytec Systems.
While camera manufacturers have developed a number of solutions specifically to combat the lighting problem, unlike many of the other challenges with video, there’s often no quick-fix for lighting. And it’s not something that can be addressed anywhere but the actual location where a video system is being installed.
“Difficult lighting conditions are probably the most challenging thing we run into,” says Vince Scarpelli, manager of product strategy for Boca Raton, Fla.-based integrator Tyco Integrated Security. “Most technology problems can be worked out, but with lighting, you can’t set it up in the office or preset cameras. You have to set it at the site.”
Further complicating the problem is the fact that the sun’s position changes from day-to-day, month-to-month and even hour-to-hour.
“One of the biggest challenges is the difference in lighting conditions during and after the installation,” says Zin Thu, product engineer for Speco Technologies, based in Amityville, N.Y. “The installer can set up a perfect installation during the time of the install, but the lighting may change as soon as the installer leaves the site.”
This is something that also challenges camera manufacturers, shares Allen Chan, senior product manager, Security Systems division, for Park Ridge, N.J.-based Sony Electronics.
“From the camera manufacturer point of view, one challenge we face is that our products are being asked to perform in a wide variety of lighting to give the best-quality picture,” he says. “Because this is security, they’re working 24/7, and the sun moves over the course of time.”
When it comes to capturing the best possible video images from a scene, uniform lighting across the field of view is the best-case scenario — for obvious reasons.
“A consistently lit scene, whether it is low, ideal or exceptionally bright, is always easier to deal with than a scene that has bright areas mixed with dark shadow areas,” says Bill Wilke, AEC support manager for Vicon Industries, based in Hauppage, N.Y. The problem with that, he adds is that “ideal lighting conditions rarely exist.”
While both bright- and low-light conditions are challenging, low light tends to be the more difficult of the two.
“Low light is challenging for any type of image capture because there’s only so much light entering the optical lens and passing through the lens aperture,” says Anthony Caputo, director of pre-sales engineering for Buffalo Grove, Ill.-based systems integrator Avrio RMS Group. “An analog camera handled low light better only because the minimal NTSC resolution was the standard for a century. It’s a tradeoff between resolution and lighting capability. It’s about the quality of the image processing and the thoughtful science behind programming the camera to handle it.”
This raises the point of analog vs. high-definition (HD) cameras in terms of low-light performance. And you may be surprised at the comparison.
“With analog, it’s much easier to deal with challenging lighting than it was 10 years ago. The technology in the chips has come a long way and software and firmware help. So they work very well,” Scarpelli says. “When the first internet protocol (IP) cameras came out, they faced the same challenge as analog did in the ‘90s with dealing with lighting conditions. Over the past couple years, that has improved as well. And for analog, wide dynamic range (WDR) has come a long way.”
While H.264 and other compression technologies are intended to reduce bandwidth usage and storage requirements, they actually accomplish the opposite in low-light situations, Seguin-Cory says.
“Compression techniques work to reduce bandwidth and storage requirements by only transmitting parts of the scene that have changed due to color or movement,” he says. “But with a noisy image due to insufficient light, each pixel is constantly moving. This fools the camera into thinking there is constant movement throughout the image and prevents video compression from working. It creates a higher amount of data to be transmitted and increases bandwidth and storage costs.”
This consideration is important — but often overlooked, says Willem Ryan, senior product marketing manager, Bosch Security Systems, based in Fairport, N.Y.
“We’re finding that in the IP age, the bitrate and bandwidth effect the camera has is just as important as lighting performance,” he says. “You may get a good image but the bandwidth is through the roof. With all the cameras on the network, that’s going to impact performance, storage and image quality. So you also have to look at the bandwidth performance.”
Regardless of today’s challenges, things are a whole lot better than they were in the past, Wilke says.
“Digital cameras have, in many ways, made adapting to the existing lighting conditions easier. In the old days, the iris adjustment was pretty much all you had to play with. Technicians would often take a light meter out to a site to record scene illumination levels to help decide what approach to take,” he says.
What’s Out There
Given the difficulty of achieving video performance in challenging lighting, it’s not surprising that there are more options available for addressing that challenge than ever before. Advances in low-light sensitivity, compression technologies, WDR, and gain control (to name a few) have made it a bit easier for designers and installers to provide solutions for most applications. However, the greater number and variety of options have also created an additional challenge of finding just the right solution for a particular situation, says Thomas McIntyre, national sales manager for Arcadia, Calif.-based LILIN USA.
“While new technology has made it easier to adapt cameras to various environments — for example, an IR camera that also has WDR for bright-light conditions or intelligent IR that adapts to different situations — the quality of the solution still rests in the hands of the person designing the system,” he says.
Of the technology solutions available for addressing lighting conditions, light sensitivity and WDR are probably the most well-known. Sensitivity, measured in lux, indicates the minimum and maximum amount of light, and WDR is the range of light, measured in decibels from lowest to highest. Each number indicates the amount of light a camera can use to produce an acceptable picture. And therein lies the rub, says James Marcella, director of technical services, Axis Communications in Chelmsford, Mass.
“There’s no standard for sensitivity and WDR; what’s an acceptable image is in the eye of the beholder, so it varies,” he says. (For more on how a lack of standards affects integrators’ ability to evaluate solutions, read “Navigate the Datasheet Dilemma” at www.SDMmag.com/beatlightingobstacles.)
“WDR is perhaps the most significant of these [advancements] relative to how our cameras process scenes that include both brightly-lit areas and dark areas in the same field of view,” says Frank Di Fina, senior vice president of sales and marketing, Samsung Techwin America, based in Ridgefield Park, N.J. “Good examples include a car with headlights moving across a parking lot at night or an office building lobby with large windows. Conventional cameras balance the overall lighting in the scene, providing an overall bad image.”
While WDR and sensitivity have the most name recognition, there are a plethora of other technologies that have been developed specifically for mitigating lighting challenges.
“The WDR sensor is obviously the biggest mover that’s advanced cameras in terms of lighting challenges, and the varifocal lens helps. Another major development is auto compensation in back-focus, which makes it so the camera can move the sensor a millimeter or so in either direction. That helps adjust the focal point for day and night,” Scarpelli says.
Optics is another of those often-overlooked considerations that’s extremely important, Marcella says.
“What lens should you put on the camera or ships with the camera? The lower the f-stop, the more light it lets in,” he says. “You also have to consider the wavelength of the light used. Typical day/night cameras use IR in the evening and IR-blocking during the day. Integrators have to make sure the lenses they’re using permit that wavelength to come through and understand that an IR-corrected lens is going to limit focus shift.”
Improvements in sensor technology are also helping to overcome lighting challenges. Five or so years ago, the increased use of megapixel cameras, driven mainly by digital photography and camera phone popularity, created a shift from CCD sensors to CMOS, which have steadily improved — again, thanks in large part to the consumer market, says Bosch’s Ryan.
“The problem at the time sensors started to shift was that CMOS was new in terms of performance. Their ability to compensate for light was really poor,” he says. “If you think back to the first digital cameras and camera phones, they were horrible in low light. If you wanted to take a picture in anything but bright light, it just was not going to happen. The proliferation of digital photography and camera phones changed that. Because of the tens of millions of smartphones out there with cameras in them, everyone put their research and development into CMOS. At the present time, CMOS is pretty good. The technology is moving forward in terms of resolution and low-light performance.”
Because they rely on temperature rather than lighting, combined with the availability of more cost-effective models, thermal cameras have gained popularity for combatting lighting challenges, says Bill Klink, vice president of business development for Wilsonville, Ore.-based FLIR Commercial Systems.
“In a situation where the camera is looking right into the sun at some point during the day, a visible light camera would be blinded or challenged. You also have situations where there are shadows or a dark corner or uneven lighting where thermal performs well,” he says. “Distance is another part of outdoor installations. Incandescent lighting will only go so far. In a parking lot or perimeter situation, if you want to look beyond 100 or 200 feet, you’re out of light. You may want to look, but you run out of gas.”
When it comes to both WDR and thermal, there are often preconceived notions that need to be dispelled, Marcella says.
“WDR is not just for daytime but it’s also used at night. Think about when you’re driving at night and another car approaches. It adds more light to the scene, but it’s more difficult lighting. That’s why WDR is typically used at night for transportation where there’s oncoming light, particularly for license plate recognition,” he says. “Thermal is just the opposite. It’s not just for night. There’s a lot to be said for using it during the day. If there’s a glare, it’s difficult to see through that, but thermal will still detect someone entering an area in glare.”
Let the Site be Your Guide
Beyond significant technological improvements, there are other ways to mitigate challenging lighting conditions, including the most basic tactic of all.
“The main thing is starting with a good assessment of the location and understanding all the lighting conditions at the different times of the day,” says Devin Benjamin, CEO of Innotech Security, located in Pompano Beach, Fla. “Secondly, I would advise pinpointing the objective you are trying to accomplish.”
Because light does change, sometimes quickly and drastically, it’s also important to understand what lighting conditions exist throughout the day, Marcella says.
“You have to understand the position of the sun throughout the day. It gets back to the basics of a site survey,” he says. “Take lux readings at various times of day. I understand this is often overlooked because of the time required to do it, but with mission-critical applications, it’s important to understand the different light level at 9 a.m., noon, 5 p.m. and 9 p.m., for example.”
Between technology and old-fashioned site surveys, there’s a way to overcome nearly every low- or bright-light challenge while meeting your customer’s overall objectives — which, despite all the available bells and whistles, is the name of the game.
Installation Rules of Thumb
- Conduct a site survey.
- Determine the customer’s goals (detection, recognition, etc.).
- Gather lux readings at various times of day.
- Add lighting where possible.
- Avoid aiming cameras directly at the sun.
- Test equipment at the site and make any necessary adjustments before installing.
- Manage expectations.
Anthony Caputo of Avrio RMS Group learned from experience the importance of testing a camera or system throughout the day while also considering changing seasons.
“If you don’t have a track record for a select camera model and technology, and this is a large deployment in challenging lighting conditions, I suggest a test pilot. Record for 24 hours and review. We once tested a military grade IR PTZ camera for a drawbridge deployment. It was up and running successfully for months, so they were implemented on all the drawbridges. Unfortunately, those months were during the summer when these cameras thrived. Come winter, the snow froze a couple of the camera’s PTZ motors which were blasted by freezing cold air from a wind tunnel. Who knew?”
For more examples of how others have overcome challenging situations, visit www.SDMMag.com/beatlightingobstacles.