In a Blur
New camera technologies eliminate nighttime blurring
- By Mike Capulli
- Apr 01, 2009
One of the major challenges in specifying a camera is dealing with low-light surveillance. End users need cameras to help them see subjects clearly while avoiding blurs. Let's look at the solution from the perspective of what end users and their integrators really want from a video surveillance system—useable video.
Good News and Bad News
The security industry has been undergoing a series of advancements in low-light surveillance. Nonetheless, image quality in these situations does not compare to the quality of daytime surveillance. It's a fact: the lower the lux rating, the higher the sensitivity to light. Yet, today's best-rated cameras, without doubt, will provide excellent, useable low-light video. We can take night images and make it look like daylight. That's the good news.
On the other hand, many video surveillance users have had the following experience: While viewing their surveillance monitor at night or in very low light, everything appears normal. Suddenly, a flash appears on the monitor. Something has happened, but the viewer couldn't identify what it was. Although the system was deploying day/night cameras, they did no provide useable video.
Other times, we can make a few things out: "We've got a guy in dark pants and a dark shirt leaving the games section. Age-wise, he's about ... um. He's got ... hair. Aw ... what's with these blurs? I can't tell a thing."
And, when the recording is given to law enforcement, they will say the same thing, as will the defendant's attorney if the perpetrator gets caught. After all, a guy wearing dark pants and a dark shirt is not much of a description. If only that perpetrator had stood still. Then, the day/night camera could have captured a nice, clear image.
What's the problem? Whether with electronic day/night modes that provide color images in good light and monochrome images in low light or true day/night modes, which provide color in both good and low light, day/night cameras have problems capturing clear moving images in low light. What you get are blurs, which are not helpful. They don't identify the perpetrator, and they don't stand up in court.
Why Does Blurring Occur?
Many cameras act as though they are underpowered. In darkness, their image processors have to spend more time trying to compensate for low-light images. Therefore, they cannot output the same picture quality they get under normal lighting conditions, resulting in deteriorated images. It's not uncommon for a camera to appear to deliver 20 to 30 frames per second in normal light but drop to less than 5 fps in dark conditions.
To explain it even more simply, these cameras deliver a clear image in low-light conditions by slowing down the shutter speed to increase the average amount of light gathered at the image sensor. However, shutter speeds also control the motion-stopping ability of the camera.
Here's where the problem arises. The more the subject moves during the length of time the shutter is open, the more the image moves across the screen.
The result? The more the image moves across the screen, the more blurred the subject becomes. To make matters worse, some frames actually will be dropped, creating a jerky motion effect.
So, with unmovable or slow-moving targets, the trade-off between the slower shutter speed and light may go unnoticed. The shutter speed can handle it, providing a relatively clear and usable image. But, once the subject starts moving, you get a blurred image again. Yes, you captured an image, but it is not usable. Your investment in the surveillance system is not paying off.
What Can You Do?
Today, you can select either electronic or true day/night cameras that will eliminate the nuisance of night-time blurring. This new breed of electronic and true day/night cameras now balances the exposure time and light collection without compromising future evidence by providing clear images in low light even if the subject is moving. These cameras let you clearly identify the perpetrator, view the getaway car or even capture the license plate. They even provide a boost from the typical 540 lines of resolution to 580 lines of resolution.
The 45 minutes that it takes to install most cameras drives up the price of a surveillance system, which is unappealing to end users and integrators.
This problem is solved by yet another new development in cameras. Today's newer cameras can be easily installed in 10 minutes.
First, install the mounting. Since the camera is already in the housing, that entire procedure is eliminated. Then connect the wiring, which is already bundled into a single cable and available at the screw-in hole for the housing. Once the wiring is connected, screw on the housing, and you're done.
Before specifying the next cameras, check with the integrator and manufacturer. The days of night-time blurs and long installs are over.
This article originally appeared in the April 2009 issue of Security Today.