Making Sense of Surveillance Claims
MANUFACTURERS tout their surveillance cameras as “HD,” “HDTV,” and “megapixel.” Companies that may want to put in a surveillance system or add cameras to an existing system need to understand what these words really mean in terms of functionality in the field.
HD (or high definition) and megapixel are related terms. To be considered high definition, a camera must have resolution that is higher than standard definition and is often at least 1280 x 720 pixels per frame, which equates to just under one million pixels per frame, commonly referred to as a one megapixel camera. Some cameras on the market can support up to 21 megapixels, but three or fewer is more common.
HDTV cameras will be either one or two megapixels, referred to as 720 or 1080 (the 1080 is a reference to the fact that 2 megapixels have 1920 x 1080 pixels per frame). The resolution will often be followed by an “i” or a “p,” depending on the type of scanning system in place in the camera.
But HDTV is a standard that covers more components than just the number of pixels. It generally means that the cameras are compliant with HDTV standards as outlined by the Society of Motion Picture and Television Engineers (SMPTE), explains Fredrik Nilsson of Axis Communications, one of the companies that markets such cameras.
In addition to the resolution being megapixel or HD, HDTV cameras must have a widescreen aspect ratio (width to height) of 16:9. Because companies often need to monitor a wide area rather than a high area, this aspect ratio may be a good fit for surveillance, says John Honovich, founder of IP Video Market Info.
Another component of HDTV cameras is that they must take video at a full frame rate of 25 or 30 frames per second, which corresponds with television broadcasting. The cameras are able to do this because HDTV cameras use H.264 compression, which decreases the data size so that the video does not overload the network the way it may have years ago.
H.264 compression becomes less popular when you get up into the higher megapixel range, according to Honovich, because it requires more computing resources than other compression methods, such as MJPEG. “The processing power needed exceeds what standard camera chipsets can provide,” he says.
Honovich points out, however, that there are a few companies that do use H.264 above 2 megapixels; one example is Arecont Vision, which developed a proprietary chip that allowed it to do so.
There are various applications that full-frame-rate streaming might benefit. “If you’re doing something in an application where people are moving quickly, whether it’s like sleight of hand in a casino or a car moving at 30 or 40 miles an hour, that higher frame rate will definitely help you,” says Honovich.
If a camera is recording at less than that frame rate, say 15 frames per second, to save space on the network, it is not technically recording to HDTV standards, even if it is HD. The lower frame rates are fine for many applications, such as parking lot surveillance.
Nilsson says another component of the HDTV standard is broadcast-level color accuracy. Color fidelity has obvious benefits for surveillance.
“HD[TV] will always be a subset of the total number and range of megapixel cameras on the market,” says Honovich, adding, “There is certainly demand for more than two megapixels. So it’s not as if everyone is going to stop doing other stuff and just focus on 720 and 1080p.”
Non-HDTV megapixel cameras, as mentioned, can go up much higher than just 2 megapixels. Additionally, it should be noted that many megapixel camera manufacturers that do not advertise themselves as HDTV-compliant still provide full frame rate recording options and color fidelity.
Steve Zielinski of integration company SDI Enterprises points out that one advantage of the higher megapixel cameras is that they offer more pixels—more data—that can be fed into algorithms for facial recognition and other analytic programs.
Honovich expects the surveillance industry to start pushing out more HDTV-compliant cameras to capitalize on the consumer familiarity with the concept. But in addition to the current limitation on megapixels, another issue that could limit the market share of HDTV-compliant cameras may be the current price levels. Honovich says that the HDTV-compliant cameras he has seen are more expensive than megapixel cameras.
Nilsson points out that the HDTV cameras often have more capabilities; however, he says Axis prices the cameras comparably to its own non-HDTV cameras of the same resolution and capabilities.
The security professionals interviewed for this article emphasize that despite the surge in attention to high resolution formats, a majority of the market hasn’t even yet made the switch to IP and needs to lay the infrastructure necessary to ensure that their organizations can implement such data-heavy, high resolution cameras onto their networks.