Deciphering Megapixels: CCTV Resolution April 5, 2016

Camera

720p/1080p, 960h, Analog, Digital,  High Definition, IP, 1MP, 2 MegaPixel, AnalogHD…

What does it all mean?

In short, resolution is the resolving power on your camera. Meaning, how sharp will the image be when you play back the recordings (evidence), and how far can you zoom into an image before it becomes blurry.

Bottom line, if you stick with Analog = 960h, you will be limited in the definition or sharpness of the image. It may look fine, and there are some excellent analog cameras but if you try to zoom in to a face 10′ away, it may look like a blur. Video compression on analog systems can also make the recordings (read – evidence) a lot fuzzier than digital. Analog resolution is usually measured in TVL (TV Lines). If buying a replacement camera for an existing system, look for 700TVL or better. It still won’t hold a candle to HD, but it will be a major improvement over older systems. There are some forms of Analog HD, but we’ll get back to that later.

When it comes to digital, here are some shortcuts (not entirely accurate, but close enough): 1mp = 720p, 2mp = 1080p. One megapixel (720p) will get you about 10′ of facial recognition. Every megapixel after that gives you another 8-10′ of facial recognition. It also means more money. So, if you have 40′ of frontage on your house, you may be better served by installing two 2MP (1080p) cameras, than one 4MP. Depending on the layout, you may actually want to look at 4 cameras to make sure that nobody is at the limit of a camera’s range.

That doesn’t mean that you won’t get an image, you will. It may even look pretty good until you try to zoom in on details, but most crimes don’t happen right in front of a camera. Remember, the main purpose of a camera system is playback of the recording. If it gives you a great live image, but gets blurry when you zoom in to an area of interest, you need higher resolution cameras.

A question that often comes up is “why do I need above 1080p (2MP), after all my TV is only 1080p.” Because, if the sharpness of the camera matches the resolution of your TV, when you view the image full screen that’s as good as you are going to get. Try zooming on the face of someone standing 20′ away and you’ll see exactly what I mean.

High Definition (HD)

High Definition (HD) is a problem term. It can be used for anything from 700TVL to infinity. I’ve seen it used on Analog and Digital cameras of vastly different quality. Basically – ignore it.

AnalogHD (AHD)

AnalogHD (AHD) can be a great technology for updating existing camera systems without investing in new wiring. There are a number of competing technologies making picking a long term winner complicated. HDSDI, HDTVI (aka Turbo), and CVI are all competing for the AnalogHD market. There is no cross-compatibility between these standards at this time. Another words a TVI camera will not work on a CVI recorder and vice versa.

To paraphrase, if you are looking to upgrade an existing camera system without re-wiring for Digital, AnalogHD may be a great solution.

HDSDI

HDSDI has proven to be finicky and may be on it’s way out. It had amazing promise of ultra high definition images over existing conventional cabling, but has proven too temperamental to use outside a studio or laboratory setting.

HDTVI

HDTVI seems to be supported by the largest number of manufacturers among the standards. There is also a lot of compatibility between the various systems. So, you could mix and match camera brands and recorder brands to build the best system to suit your needs. The major drawback seems to be that current HDTVI systems are limited to 1080p (2MP) resolution.

HDCVI

HDCVI presents a more interesting situation. The standard is patented by a single manufacturer and everyone else has to license it from them. Consequently there is only a handful of products on the market with this technology. It still has a lot of potential, but while live view images seem sharper and brighter than TVI, playback of recordings (evidence) appear fuzzier and lower quality.

Digital/IP Cameras

IP or Digital cameras are the cutting edge of current technology and appear to represent the future of the CCTV industry. Delivering a digital image with seemingly endless resolution (30MP cameras are already on the market) over a single cable is just the beginning. The single cable is thinner than traditional analog cabling – making it easier to install in challenging spaces – provides both two-way communication with the camera and also the power to the camera. It can also allow adding new cameras to the system after the initial installation without having to run the new cables all the way back to the recorder.

There are many other exciting features that IP cameras bring to the game. We’ll go over them in a separate segment.

IPoCOAX

IPoCOAX may be the ultimate in upgrading an existing analog system. The various media conversion systems allow existing analog wiring to be used for a full IP/Digital upgrade. Imagine upgrading your parking lot or warehouse camera to a 5MP, 8MP, or even 12MP camera without re-running the wiring in the rafters.

Next we’ll get back to lighting…

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