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HDTV stands for High-Definition TeleVision and it should mean better quality pictures and surround sound. The proponents of HDTV say that viewers will be able to see ‘individual blades of grass on a football pitch and the details of faces at the back of a crowded stadium – as well as the beads of sweat on Cristiano Ronaldo’s neck’.

It has been suggested that the revolution could mean some TV celebrities becoming unemployed because the higher picture quality will show up facial blemishes that are missed by existing televisions. The real benefits of HDTV viewing will come in watching visually spectacular programmes, such as Hollywood movies, natural history documentaries and sport.

How does HDTV work?

High-definition screens are higher resolution – they have more picture elements or pixels per square inch – giving clearer pictures that contain about four times as much detail than existing television images. They do this by packing in more horizontal lines on the screen. Existing standard definition TVs have 576 horizontal lines but HDTVs have between 720 and 1,080 lines. Most HDTV sets being sold now in India are of the 720 format, although a few can screen the 1,080 format.

Where does widescreen and digital TV fit in?

They are all related. You need digital transmissions to transmit the higher quality broadcasts of HDTV and the benefit of these are best seen on wide-screen sets that project a “letter-box” shaped image. This shape is known as the aspect ratio. Standard television sets have an aspect ratio of 4:3, meaning that if the television screen is 16 inches wide then the screen will be 12 inches high. High-definition television uses higher aspect ratios, usually 16:9, so that films and programmes can be viewed in a form that is nearer to theatrical dimensions (ie. without cutting off the sides).

Is flat-panel television best?

Not necessarily, but the confusion is understandable because HDTV is only worthwhile if you have a big screen, and flat panels make it possible to have bigger screens. Conventional televisions use cathode-ray tubes, which stick out like the back of a bus. The bigger the screen, the more it sticks out behind, which makes life difficult if you want a big screen in a small living room. The newer flat-panel TVs use either plasma screens or LCD (liquid crystal display) technology rather than cathode-ray tubes. Both types of technology can be used to make big screens that are thin enough to hang on a wall – good for seeing the benefits of HDTV. However, the Korean television company Samsung has now designed a “slim-fit” cathode-ray tube television that is less than half the thickness of an ordinary television set. This set is also designed for HDTV and experts say that its picture quality may even be better than plasma screens and LCD sets.

Is HDTV best seen on a big screen?

In a word, yes. Don’t expect to see a dramatic difference if you go for an HDTV with a screen smaller than 32 inches (TV screens are measured along the diagonal). One study of people watching television at various resolutions concluded that at normal viewing distances and normal-sized screens, people did not easily discriminate better resolutions than those currently used. To get any benefit from high-definition TV you need a bigger screen or to sit much closer to it.

A full Freeview service of HD broadcasts is not possible at present because there is not enough bandwidth space in the transmission spectrum. Only when all analogue channels are turned off between 2008 and 2012 will there be enough space to accommodate HDTV channels.

Should you buy an HDTV set now?

As it will be many years before you can watch HD broadcasts – unless you are prepared to subscribe through a satellite or cable channel – it might be worthwhile waiting a bit longer until prices come down further – and the day of universal HD broadcasts comes closer. But if you need a new TV now, be sure to get one that is marked “HDTV ready“.

A short history of television

1884 Paul Nipkow creates the first scanning rotating disk, which provides a way of sending a representation of a moving image over wire using varying electrical signals.

June 1908 A A Campbell Swinton writes to the journal Nature, proposing a system of electronic television, based on the recently-developed cathode ray tube.

October 1925 Scottish inventor John Logie Baird, the acknowledged father of television, achieves a clear, greyscale image for the first time, using a ventriloquist’s dummy head, nicknamed Stukey Bill, as the subject.

1932 The BBC begins the first regular television transmissions, from Broadcasting House.

1967 The BBC begins the first colour transmissions in Britain.

1990s Digital television begins with the first satellite, cable and terrestrial services. Analogue signals will be switched off in 2012.

 

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