CCTV camera sensor manufacturer Pixim has produced an interesting

white paper explaining that:

Camera manufacturers are advertising specifications of 580, 600, 650, and even 700 HTVL, and some of these manufacturers are making these claims even though they are using imaging sensors that are not physically capable of capturing more than 540 HTVL; the practical limit for analog CCTV systems.

HTVL = Horizontal TV (TeleVision) Lines (the measure which is most simply explained as – if you run your finger horizontally across your screen the maximum number of vertical black/white lines that you can resolve).

Visit the Pixim website to download the white paper now.

Pixim make sensor chips. They should know what they’re talking about!

If it raises any queries, please feel free to use the comments below.

CCTV cameras that connect via a BNC connector have a maximum colour image resolution of 540TVL.

CCTV cameras that use an RJ45 connector, and are therefore called IP or Network Cameras, do not necessarily offer a higher resolution!

You need to check the spec – 540TVL approximates to 0.4 megapixel.

Analogue CCTV security camera manufacturers express the resolution of their products in terms of TVL, which stands for TeleVision Lines.

A good modern high-resolution CCTV camera will have a resolution capability of about 540 TVL.

What this means is, if you ran your finger across a CCTV monitor you would (if you could see them) be able to resolve 540 vertical lines.

IP camera manufacturers express the resolution capability of their cameras in terms of pixels (in the same way that computer monitor manufacturers do).

A typical current model IP camera might have a resolution specification of 1280 X 1024 pixels.

The first digit expresses the pixel count across the screen (the horizontal resolution).

The second figure expresses the pixel count top to bottom.

Multiply the two together and you get 1,310,720 or 1.3 million or 1.3 megapixels.

540TVL equates to approximately 0.4 mega pixels.

Five years ago the maximum TVL for an analogue CCTV camera was 520TVL – we have effectively reached a ceiling in terms of analogue CCTV resolution!

The best IP CCTV cameras your money could currently buy deliver 16 megapixel images.

Network cameras with 1.3 megapixel sensors are now common.

Two, three and five megapixel cameras are all also readily available.

Your mobile phone is very likely to have a 3 Megapixel camera built-in.

A pocket digital camera wil have a snesor resolution between 5 & 8 megapixels.

A professional digital SLR will deliver 12 megapixels or more.

The bleeding edge in CCD image sensors is currently resting at 60 megapixels!