One of the most rapidly changing aspects of video surveillance today is the improved performance of low-light cameras, which have made tremendous strides in leaving behind the bad memories of poor performance that pervaded the space just a few years ago.
In the early days, cameras’ low-light video typically consisted of monochrome or black-and-white video, supplemented by external white or IR lighting. This severely limited the visual data that could be pulled from it and reduced video to flat imagery, says Jeff Whitney, vice president of marketing, Arecont Vision Costar, Glendale, Calif.
“When the best possible video was needed from a single camera for both day and night, some vendors offered dual-sensor cameras with one WDR (wide dynamic range)-capable sensor for high-contrast daytime use and another black-and-white one for nighttime use, switching between them at a preset lighting threshold,” he says. “While these technologies continue to have some play, newer technologies have made big strides in improving low-light imaging.”
Not surprisingly, the poor performance of past security cameras in low-light situations was historically a headache for integrators, says Doug Gray, product marketing manager, Hikvision USA, City of Industry, Calif.
“Fortunately, low-light technology has greatly improved in recent years, with some notable achievements just in the past year,” he says. “For example, cameras can now provide color images in low-light — an important new tool for a security director.”
The overall improvement in low-light performance is due in large part to the combination of advancements in individual areas.
“Today’s low-light performance is far better than cameras of yesteryear: Higher frame rates, higher resolution and longer range represent some of the advancements,” says Tim Eng, product manager, Speco Technologies, Amityville, N.Y.
In fact, today’s cameras have evolved to the point where color images are possible at light levels that would have been unheard of in recent past.
“The advancements in low-light technology have greatly improved sensitivity in today’s IP cameras and enabling capabilities to capture color images in as little as 0.1 lux,” says Jeremy Kimber, director of global commercial video, Honeywell Commercial Security, Melville, N.Y. “Previously, only monochrome IR images were possible at these light levels.”
Additionally, as low-light technology has matured, manufacturers have introduced a variety of cameras that are accessible to customers at different levels.
“Highly effective low-light technology is now available at a variety of price points, so that SMBs as well as enterprise customers can improve security using this new technology,” Gray says.
Perhaps the biggest factor in driving better low-light performance can be traced to enhancements in sensor technologies.
“Improvements in sensors have made a major difference,” Whitney says. “4K is growing in familiarity, while 5- to 12-megapixel single-sensor cameras have become increasingly common. The sensors in these cameras have higher pixel counts and are much more sensitive than their predecessors, able to provide superior imagery day and night, all by themselves.”
Of particular note is the industry-wide shift from CCD to CMOS sensors, which are not only less expensive to manufacture, but also offer a more flexible approach in how pixels are read and processed.
“Back in the day, CCD was great; it was amazing,” says Steve Burdet, team lead, solutions development, Axis Communications, Chelmsford, Mass. “But CMOS enabled us in the digital space to be able to do more, and it’s created a huge trajectory path.”
In addition to the move to CMOS, some sensors today are purpose-built for light sensitivity.
“The addition of back-illuminated sensors has resulted in improvements to sensitivity by placing the sensitive surface on the opposite side of the camera to the chip wiring, ensuring more light reaches the pixel,” says Jennifer Hackenburg, senior product marketing manager, Dahua Technology USA, Irvine, Calif.
An increasing number of general surveillance camera vendors are exploring a number of new sensor types that could be added for further improvements, including for day/night use, Whitney says.
“Instead of expensive and very limited-use thermal cameras, more vendors are exploring adding thermal imagers, RGB color sensors, and even more, all potentially to be combined with traditional image sensors,” he says. “These developments will add more useful video and other data, while maintaining affordability.”
In addition to camera sensors, improvements in chipsets also have gone a long way toward providing additional processing power to run more complicated algorithms for low-light image processing to render more activity and better adjust to scenes.
“The camera can take that information and process it in a much more effective way to produce cleaner data,” Burdet says. “Where you have a high level of noise, you can’t run some of these advanced technologies, because all they’re going to do is amplify the noise. But if you started with reduction of noise, you can reduce that much more substantially.
“It’s almost a compounding effect, because you’re able to have a higher degree of confidence in the other pixels. The ability to reproduce low-light images in highly detailed color has been a key factor in driving the continued improvement and evolution of low-light cameras.
If I don’t know which pixels out of a group of 100 I can trust, that’s going to make it much more difficult. But if out of that I can trust 80 or 90 or more percent of them, I can run a lot more complicated things because I’ve got more buffer room for myself, which is huge,” he adds.
Color in the Dark
Technologies that deliver color images in low-light situations have been on the market for a number of years, and have dramatically increased the amount of video data that can be obtained from an image, adding the high level of detail that color can provide.
“Advanced low-light cameras can now provide full color images in the dark — even down to 0.0069 lux,” says Paul Garms, director of regional marketing, Bosch Security and Safety Systems, Fairport, N.Y. “Color images in low-light conditions are important, as they aid in identification capabilities, such as for determining the color of a vehicle or of an article of clothing worn by a person of interest.”
More recently, Whitney says, color nighttime imaging has become prevalent in multi-sensor cameras, combined with integrated IR illuminators in the some of the best models.
“Just as for daytime applications, multi-sensors reduce the number of cameras and infrastructure required, while providing continuous surveillance of the entire area, and making the camera more useful at night time is important to many customers,” he says.
The Importance of Testing
As is the case with most specific deployments, the number one rule when working in low-light conditions is to look beyond manufacturers’ spec sheets.
“Don’t rely on data sheet specs to determine the performance of a camera. It is extremely important to test cameras either in the environment in which they will be installed or in an area with similar light levels and patterns to determine actual performance,” Garms explains.
“We all know that a picture is worth a thousand words, but in the world of low light, sometimes that picture isn’t quite clear,” Hackenburg says. “There isn’t a single answer to the difficulties presented by low-light environments; therefore, it’s always best to demo the product in the native environment to ensure user expectations are met.”
When testing cameras, it is important not only to demo them during the daytime but at night, as well.
“Cameras that look fantastic during a daytime demo can disappoint users once the lights go down,” Hackenburg says. “In low-light scenes, image noise increases bit rate, resulting in poor images and a higher strain on the network. Additionally, when light is lowered, frame rates drop and exposure time increases.”
Another reason to test is to be sure the camera’s resolution does not change in low-light or dark situations.
“Some manufacturers use an old industry trick and lower the camera’s resolution at night. By lowering the resolution, the size of every pixel increases, which in effect, allows more light to enter the camera. This will work if the end user is not concerned with evidentiary images,” says Tony Dimids, product manager, edge devices, FLIR Systems, Wilsonville, Ore. “My advice would be to select a camera that will perform well in low light and maintain the resolution expected.”
In addition to testing low-light capabilities, security integrators also should look at the various technologies and systems with which the camera will be integrated to ensure proper performance.
“Testing cameras from various manufacturers for real-world comparison is the key, for low-light as well as VMS integration and ease of installation and use,” he says. “Ensure that the camera selected is ONVIF-compliant, and works well with your VMS of choice, and perhaps a backup VMS selection as well in the future. A camera that only works well with a single VMS is not a real benefit to the customer as it limits their future choices and project development.”
Given the continued, rapid advancement of low-light technology, there may be a temptation to pull a camera out of the box, install it and expect it to work perfectly, Burdet says.
“I’m confident that in the majority of scenes it will work fine and meet their expectations, but you’ll run into that percentage of situations that are just more complicated, where there’s something in it that’s making it more challenging,” he says.
These challenges might include a complete lack of lighting or differing light dynamics, such as a mix of IR lighting and street lamps, which can create difficulties for the sensor to capture light optimally.
“It’s important to understand that camera settings and the software and algorithms they employ are not static,” Burdet says. “You can make changes to adjust it to the scene if it doesn’t meet the needs of the scene immediately.”
This is particularly important when evaluating cameras, as different manufacturers’ offerings offer different levels of customization.
“Many premium-branded camera manufacturers use advanced optics and an off-the-shelf high-quality sensor that can increase light sensitivity dramatically,” Hackenburg says. “However, the ability to then tweak and fine-tune the process is what differentiates one manufacturer from another.”
The bottom line, Burdet says, is no matter how good the technology may be, integrators should at least look at its customization capabilities to determine the best fit for a site.
“Don’t go in thinking that it’s going to be the best out of the box. It can be phenomenal, but if you’re not happy with it, don’t think that it’s broken and just throw your hands up. You have the opportunity to make it phenomenal for yourself,” Burdet says.
Looking to the Future
Low-light technology has moved a long way from just a few years ago, and the technologies that drive vendors’ offerings will continue to change in the coming months and years.
“Both single- and multi-sensor cameras now offer improved low-light technology, and the availability of color imaging at night is important in providing more useful information,” Whitney describes. “Stay tuned, and continued improvements in sensors, algorithms, and soon AI technology will all contribute to even better products in the future.”