Firstly here is a fairly comprehensive list of all the technical specifications that you might come across and what they mean
High-definition television (HDTV)
HDTV is a new system that transmits a TV signal with roughly twice the standard picture resolution as normal standard definition telly. Both Sky (satellite) and Telewest (cable) operate HDTV channels. To watch you need a subscription to either one of these services and an 'HD ready' TV. However, not everything on the dedicated HD channels is actually recorded in HD. More programmes are being recorded in HD all the time but content can be a bit thin on the ground.
Contrast Ratio
The higher the number the greater the difference between the brightest and darkest pixels. The greater the difference the greater the potential for higher image quality.
Pixel Resolution
The number of pixels left to right and top to bottom. Generally speaking a higher number offers the potential for a higher quality picture.
Brightness cd/m2
Like contrast the greater the potential brightness the greater the potential for a higher quality image.
Audio power output (RMS)
The higher the figure the louder the output (usually) before distortion occurs.
HD ready
'HD ready' is a labelling scheme introduced by the TV manufacturers' organisation, the European Industry Association for Information Systems (EICTA). The label means the TV has the minimum screen resolution (at least 1280x720) and digital sockets (HDMI or DVI) to receive and display an HD picture.
plasma
A plasma display is an array of tiny gas cells sandwiched between two sheets of glass. Each cell acts like a mini fluorescent tube, emitting ultraviolet light which then strikes red, green and blue spots on the screen. These spots glow to build a picture.
Native/screen resolution
This is the number of pixels or lines displayed on the screen. Expressed as width x height.
Aspect ratio
The shape of the screen (width x height). The vast majority of TVs are now wide-screen with an aspect ratio of 16:9. Older TVs and some portables have an aspect ratio of 4:3. Digital TV is broadcast in a widescreen format.
Auto-format switching
It's a good idea to choose a widescreen TV that automatically alters how different broadcasts are displayed – for example, showing standard (4:3) broadcasts with black bands on either side so the images aren't stretched out of proportion. Most widescreen TVs will do this.
Picture enhancement features
Be wary of these digital effects, designed to make pictures sharper and movement smoother. Our tests show they sometimes degrade picture quality.
Text and digital text
With a set-top box or integrated digital TV, you can access the digital text services available on some digital channels. These look like internet pages, and some let you watch an inset of the TV picture at the same time.
Picture in picture (PIP)
Picture-in-picture displays a small image in the corner of the screen while you watch the main image. Some TVs let you watch another broadcast channel in this way – so you can check the progress of a match, say.
RF input
This is the socket for your aerial and allows the broadcast signal to be received by your tuner.
Scart with RGB
Scarts are the best way to connect equipment like DVD players and VCRs to your TV. Most TVs now come with at least two Scart sockets. If you need more, you can buy a Scart switching box for £10 or so to expand your TV's capacity.
For the best picture, look for Scarts that support the high-standard RGB signal. This splits the video signal into its red, blue and green components to give an improved picture.
Video and S-Video
If you're short of Scart inputs composite video and s-video can provide an alternative. S-Video signals are split into colour and brightness but are slightly inferior to Scart RGB.
Composite video
Both let you plug other AV equipment, such as camcorders and games consoles, directly into your TV.
HDMI input
If you're interested in HD this is the high-capacity input for high-definition video and audio signals. Two HDMI sockets mean you could plug in both an HD set-top box and an HD DVD player.
DVI input
This is the standard digital input used for high definition video. Unlike HDMI it cannot carry audio signals.
VGA input
VGA input to connect your PC
A VGA input lets you connect your PC - effectively turning your TV into a PC monitor. Digital DVI sockets provide an alternative but in our tests VGA looked better on the screen. DVI can over enhance the picture, making it too sharp.
Component video input
This is a high quality video input made up of three sockets coloured red, green and blue. Also known as YPbPr, it splits the video signal into three separate parts for an improved picture.
However, component connections are still not widely used on AV equipment and unlike Scart sockets they do not carry the widescreen switching signal.
Phono sockets
These red and white sockets allow you to connect your TV to a stereo amplifier - useful if the built-in speakers aren't quite up to the job.
Surround sound
Some TVs come with an extra set of speakers you place away from the set to create surround sound. Many other TVs have 'virtual' surround sound: they mimic the effect using the two main speakers, but this is usually disappointing.
Optical output
If you want to connect your TV directly to a surround sound system there are two types of digital connections - coaxial (wire) and optical (fibre optic). Make sure your surround sound system input matches the input on your TV.
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