HDTV BASICS

Since the first HDTVs appeared in 1998, high-definition television has been on the mind of every TV buyer. The big question is whether now is the time to pay a few hundred to a few thousand more and take the plunge on an HDTV set.

Analogue, digital and HDTV

Analogue: An analogue TV cannot display progressive-scan DVD or HDTV. It can show only standard-definition programmes such as those found on ordinary TV, cable, satellite or Freeview.

Digital: A digital television, or 'DTV', can display Freeview broadcasts from an internal digital tuner.

HDTV: True high-definition televisions, or HDTVs, can display standard TV, progressive-scan DVD, and HDTV signals. To be considered true High Definition TVs, compatible with Sky's forthcoming High Definition service, they must have an HDCP compliant digital input, as well as at least 720 lines of physical resolution.

Receiving High Definition content

This year is when high definition really kicks off, with Sky's HD service, Sony's Blu-ray system and Toshiba's HD-DVD all set to launch.

While there may not be a lot of material out there, luckily it's easy to get hold of. Anyone with a reasonably fast computer (2GHz processor and above) can download film trailers and assorted clips from Microsoft, DivX, or if you're a Mac user, from Apple. You can then watch these clips via your computer monitor, or connect to your digital display if you have one.

There is also a European broadcaster called Euro1080 which has been transmitting high definition content for over a year. However, you need to point a minidish at a very specific orbital position and then invest around £200 in a decoder box. It's something of an effort to set up and the channels don't offer a 24-hour service. If this sounds too much of a hassle, you'll be better off waiting for Sky's HD service.

It has been fairly well publicised that the government will be switching off the analogue television signal to make way for nationwide digital coverage. While it's true that this is the government's plan, it is a long process that won't be completed until 2010. The biggest problem is that 20-25% of the population will not be able to receive Freeview unless the analogue switch-off gets underway.

The planned switch-off will be a phased process that will take place region by region. It has already been tested in some parts of Wales and will continue to happen on an increasing scale until a country-wide switch-off occurs in 2010. While this will obviously make a lot of portable televisions redundant, it will allow more of the signal bandwidth to be occupied by digital services, so you should be able to look forward to more diverse content on Freeview in the future. Over the next few years, it is also hoped that the number of integrated digital TVs (IDTVs) will increase, while set-top boxes (STBs) will continue to fall in price.

HDTV resolutions

Resolution, or picture detail, is the main reason why HDTV programs look so good. The standard-definition programming most of us watch today has, at most, 576 visible lines of detail, whereas HDTV has as many as 1080. HDTV looks sharper and clearer than regular TV by a wide margin, especially on big-screen televisions.

It actually comes in two different resolutions, called 1080i and 720p. One is not necessarily better than the other; 1080i has more lines and pixels, but 720p is a progressive-scan format that should deliver a smoother image that stays sharper during motion. Check out our comparison chart to see how HDTV stands up against standard TV and progressive-scan DVD.

 Videophiles are quick to point out that not every HDTV can actually display all the resolution of an HDTV programme. That's true; all but the most expensive sets with 9-inch CRTs, LCoS engines, or the very highest-resolution DLP and LCD panels are incapable of resolving every detail of 1080i material. Plasma, LCD, LCoS and DLP TVs have a fixed number of pixels, known as native resolution, and the higher that number, the more detail you'll see. Naturally, higher-resolution fixed-pixel displays cost more money. At the end of the day, though, even the staunchest video critics will admit that a high-definition picture on any HDTV looks far superior to normal TV.

Normal TV and DVD on an HDTV

Normal TV on an HDTV: Aside from being able to display high-resolution HDTV programmes and movies, a high-definition set can also make normal TV look a little better. Almost every HDTV has a processor that takes the normal TV image and converts it to progressive-scan for a more stable image. This conversion won't work miracles, however, and many HDTV buyers are disappointed by how normal television looks on their new sets. That's because the big screen exaggerates the flaws in standard TV programmes. No matter how nice a TV you buy, there isn't much you can do to make normal TV, including digital cable or satellite, look better.

DVD on an HDTV: Since HDTV isn't widely available yet and converted TV doesn't really exploit the full potential of a new high-def television, you may wonder why people buy HDTVs today at all. Most of them will probably tell you it's because of DVD. HDTVs can make DVD, a very high-quality source, look spectacular. Progressive-scan DVD players have their own internal processors that are generally superior to the ones inside most digital sets. Mating a prog-scan DVD with an HDTV will give you the best picture you can get outside of HDTV itself.