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HDTV Guide

  

Introduction

  

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HDTV in the UK

High Definition TV

Today in the UK we are witnessing the start of a revolution that will transform our television viewing experience. That revolution is HDTV (High Definition Television) and it is with us now albeit in a limited form.

This new technology offers truly superb picture quality with a depth and clarity that has to be seen to be believed. Conventional TV’s which use the PAL standard, with 576 visible lines, offer a level of quality that doesn’t come close to the 720 or 1028 lines offered by HDTV.

The difference in quality is made more obvious when you compare the total number of pixels (the individual dots that create a picture) provided by PAL with 720 across and 576 vertically and Full HD with 1920 across and 1080 vertically. PAL offers a total of 414,720 (720 x 576) pixels while Full HD (1920 x 1080) offers an astounding 2,073,600 pixels.

Note: You may have already started looking at HDTV's in your local electrical showroom and noticed that they come with different resolutions, usually 1366 x 768 and 1920 x 1080; does this mean that the 576 lines (PAL) coming down through my aerial will not work with my new HDTV? Don't worry! You don't have to be concerned with matching an incoming TV signal with the resolution of the TV screen.

Your new HDTV will take the incoming 576 lines from a PAL signal and 'Scale' it to fit the resolution of your screen; in the case of a TV with a resolution of 1366 x 768, it will take a Sky HD signal (1080 lines) and scale the signal down to fit the screen.

How does HDTV it work?

Instead of using the conventional 576 lines to plot a TV picture, HDTV uses 720 or 1080 lines. In addition, the pixels in each of those lines are closer. This results in a hugely improved picture quality, clarity and colour definition.

Standard Definition v High Definition

Note: Remember that the quality of your picture depends on the source of the broadcast as well as the quality of your TV. You can watch Freeview (576 lines) on a Plasma or LCD screen, but the quality will not be as good as Sky HD (1080 lines). A Plasma or LCD TV will actually scale whatever source it is fed to fit the screen. The quality of the scaling mechanism of an HDTV differs greatly from manufacturer to manufacturer and model to model, producing widely differing results in terms of picture quality.

Is high Definition just for TV's?

In parallel to the introduction of HDTV services, consumers can take advantage of the 'Blu-ray' High Definition DVD format.

Hook up a Blu-ray player to your TV, insert a Blu-ray disc and prepare to be impressed. The picture sharpness and level of detail is simply astounding. Most new film releases are now available on Blu-ray.

If you would like to find out more, you might like to red our Blu-ray Guide.

Another area of interest within the high definition revolution is gaming. Microsoft’s xbox 360 is already HD compatible with an optional HD DVD drive. Sony's PlayStation 3 comes equipped with a Blu-ray drive as standard.

Manufacturers such as Canon and Sony have recently launched a range of High Definition camcorders which has further expanded the possibilities of working with this exiting new format.

If you would like to find out more, you might like to read our HD Camcorder Guide.

The differences between 720p, 1080i and 1080p

HDTV broadcast pictures come in two formats. The first is 720p ("p" stands for progressive), which is an image comprised of 1280 lines along the horizontal by 720 vertical lines. It shows the whole image in a single frame – that is, progressively.

The second is 1080i, which measures 1920 x 1080 lines and is displayed as two fields that are interlaced. You get a bit more detail with 1080i but the interlaced image is not as smooth as a progressively scanned one.

A high-res screen with at least 720 lines will show both formats but only a 1080-line screen will show 1080i footage at its best, i.e. in an un-scaled form.

As far as Sky is concerned it will be down to the programme maker to choose which format to use.

The 1080p format, which is the absolute best form of HD is not used by broadcasters. Movies made in 1080p (e.g. the last three Star Wars films) are starting to appear in Blu-ray format. Sony's PlayStation 3 produces 1080p output.

There are more and more 'Full HD' screens (capable of displaying 1080p) appearing. A 1080p screen can de-interlace a 1080i signal or upscale a standard definition one. With very few 1080p sources available, the main benefit of a Full HD screen is its ability to map a source such as Sky TV (1080i) pixel for pixel to the screens resolution (ie 1920 x 1080).

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What next?

So where does this leave the ordinary consumer like you or me who is interested in being part of this exciting revolution? The rest of this guide looks specifically at HDTV and takes a step by step approach to the point where you can confidently buy the kit that is right for you, and start enjoying the HDTV experience.

If your interest is directed towards the other HD technologies mentioned above there is a HD-DVD guide, and a HD Gaming guide. We also have a HD Technology section which has been designed to optimize and enhance your HD viewing experience …

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