Megapixel Definition
Megapixel resolution – what do we mean by megapixel?
Before network IP CCTV cameras came along the resolution of traditional analogue CCTV cameras (connected by co-ax) was measured in TeleVision Lines (TVL).
This TVL parameter indicated that if you ran your finger horizontally across a CCTV image this would be the number of vertical lines that you would be able to resolve. Obviously, the higher the number the greater the level of detail indicated.
The highest specification analogue colour CCTV cameras currently available can resolve to 540-560 TVL. Monochrome (black & white) analogue CCTV cameras perform slightly better and the best will claim somewhere around 620TVL.
Just to put these analogue TVL figures in perspective with the current IP camera performance – 540TVL is equivalent to 0.4 Megapixels.
Pixels is a term of resolution used commonly in the IT world. Computer monitors will have their resolution specified by means of a horizontal and a vertical pixel resolution e.g. 1440 x 900 pixels.
Digital still cameras also express their resolution capability in terms of pixels, of course nowadays these too all deliver megapixel images.
A typical megapixel IP CCTV camera might have a resolution specification of 1920 x 1080 pixels.
If you multiply the horizontal (1920) by the vertical (1080) pixels you get a total pixel count of 2,073,600 pixels.
This value may also be expressed as 2.073 Megapixels (Mega equals millions).
It is interesting to note that the co-ax connected analogue CCTV camera has been stuck at or below the current glass ceiling of 560TVL for about the past five years.
In an era when you can readily purchase a mobile phone with a built-in 8 megapixel camera, why would anybody install a security imaging solution based upon co-ax which is unlikely to ever exceed 1/20th of the performance of a mobile phone?
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Tags: CCTV image resolution, high-resolution, megapixel, megapixel camera, security cameras, video over IP
November 25th, 2008 at 9:15 pm
“why would anybody install a security imaging solution based upon co-ax which is unlikely to ever exceed 1/20th of the performance of a mobile phone?”
Cause it’s cheap?
November 25th, 2008 at 9:34 pm
Hi John,
“Cause it’s cheap?”
Not in the long run.
Not according to Axis ROI studies.
Not if you’re hoping to ID criminals and gain convictions (and thereby some worthwhile deterrent value!).
Not so much cheaper that it’s worth limiting your future options (to co-ax and analogue CCTV).
Not if you already have an IP network but need to pay somebody to install co-ax.
Not if you have to pay registered electrical installers to provide the power supplies when you could have used POE.
But above all else – think about the image.
Delighted to chat with a UK installer today who has started a school CCTV system with three Avigilon 5MP col/mono cameras and Avigilon recording software on a dedicated PC. It sits alongside their old analogue CCTV system and they’re blown away by the quality!
December 14th, 2008 at 10:24 pm
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