Bringing Megapixel Market Into Sharper Focus
Megapixel and HD video surveillance is growing at one of the industry’s fastest clips and lends itself to evermore applications. With resolutions achieving optimal levels, the rush is on to enhance image quality via complementary technologies. Find out how to best match today’s variety of imaging options with the intended purpose.
The market is filled with megapixel cameras that can only deliver lower frame rates. While you may have a camera that provides a high number of pixels, the lower frame rate will make the video look choppy. This is why in an electronics store the employees in the television aisle talk in HDTV while the ones in the point-and-shoot digital camera aisle talk in megapixel.
Additionally, if you compare color images from different manufacturers with similar resolutions, in most cases you will find that color rendition is vastly different and may not even be a good representation for actual color in the scene. How useable is an image if a black car is rendered as purple or a red coat looks orange?
Next time you are at the store take a close look at the TVs on display and the various manufacturers’ video quality. You will probably see some differences in contrast or brightness, but focus on the color from one screen to the next. You should discover that the color differences, if discernible, are so similar that you would not mistake a Baltimore Raven for a Minnesota Viking on uniform color alone.
HDTV standards increased the viewing experience to such a degree that people were willing to purchase new sets even if they had a perfectly functioning TV. That same level of quality has been attainable in surveillance video for many years with price points now reaching analog camera levels. With the combination of increased resolution, broader color rendition and higher frame rates, HDTV cameras add another level to the idea of image usability.
Megapixel Market to Remain Strong
HDTV does not herald the end of megapixel cameras any more than megapixel was the demise of standard resolution. It is just another option for professional integrators to consider during the assessment of a customer’s needs. For instance, a single 1,080p HDTV camera mounted above the center of a tennis court could be used to detect (.5 pixels/in
ch) a person walking onto the playing surface, assuming the field of view covers the length of the court. But the same camera in the same location covering a football field would not deliver the same results based solely on pixel density.
Is it possible to cover a football field with one camera and detect a person walking onto the field? The answer is yes — even if you exclude the use of thermal solutions. A football field is 3,600 inches long excluding the end zones. Based on the SKL reference, you need .5 pixels per inch for detection, which equates to 1,800 pixels spanning the length of the football field. In this case you would need a 5-megapixel camera placed around the 50-yard line with a field of view that covers the length of the field in order to achieve the desired result.
This proves that megapixel is not dead — you just need to know which resolution and frame rate will meet the end user’s needs. Still, statistics show that HDTV 720p is the predominate resolution deployed beyond standard resolution cameras today. As an integrator, it is easy to explain to people a quality level that they witness at home while watching the evening news or football game. At the same time, it is incumbent on the integrator to assess the need of a given operational requirement and ensure that the camera delivers the required resolution.
Image usability is based on operational requirements, but note that does not take into account environmental factors that can limit camera selection. Lighting conditions are a prime example of an environmental factor that can place restrictions on the operational requirements of a scene. Adding supplemental light to a scene is not always an option, making identification all but impossible at night — and the more pixels on a sensor, the more light that’s needed to activate them. Traditional day/night cameras also switch to black and white, further limiting details that can be garnered from the video.
However, recent advancements in sensor, image processing and lens technology have improved to the point where some IP cameras are able to render color images down to .05 lux (less than a full moon lighting the sky). Knowing that a person is wearing an orange coat with a red hat could be the difference in apprehending a purse snatcher who fled the railway platform at night.
This technology at its most light sensitive has been limited to extended D1 resolution, which is a fraction of a 1-megapixel camera, but the addition of color greatly increases the usability of the image at night. Continuing education is essential for integrators to stay knowledgeable about these technology advances and maintain a competitive advantage by offering solutions of which others are not aware.
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