What is HDTV and why are people buying it now?

What is HDTV?
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.

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.

Why are we talking about it now?
Britain, indeed the global television audience, is in the midst of World Cup fever and everyone wants to watch their football on the best possible television screen. In the past four weeks alone retailers have sold a record 364,000 flat-panel TVs worth Ł250m, up Ł153m on the same period last year. Sales of TVs were up by 80 per cent over 2005, with sales of liquid crystal display units more than quadrupling. Rob Shaw, a sales executive from Samsung, the world's biggest television manufacturer, says: "Several factors have come together all at once - flat-panel TVs, HDTV and the World Cup - and sales are flying."

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 Britain are of the 720 format, although a few can screen the 1,080 format.

Where do 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.

Are HDTV programmes on air now?
Owning an HDTV does not mean that you will automatically be able to watch high-definition television. In fact high-definition broadcasts will be extremely limited for some time to come. Sky, the satellite channel, and Telewest, the cable channel, are preparing to transmit HD programmes to their paying subscribers who have signed up for the service and bought a box that can decode the signals for an HD-ready set.

The BBC, ITV, Channel 4 and Five have teamed up to participate in the first HD broadcast trial this summer.

The BBC will broadcast its 2006 World Cup coverage and major Wimbledon matches in high definition this summer as part of the trial. The first live HD programme will be the opening World Cup match between Germany and Costa Rica this Friday. However, these HD broadcasts will only be to the few satellite and cable subscribers who pay for the privilege. A limited trial of HD broadcasts received via Freeview - the digital terrestrial TV service - is about to be conducted on a few hundred residents in London who have been chosen to take part in the trial.

However, a full Freeview service of HD broadcasts is not possible at present because there is not enough bandwidth space in the transmission ********. 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".

normal sets display half of the 576 horizontal lines in an alternative pattern but 'progressive scan' Tv sets with component input/dvi/hdmi input can dipslay all the horizontal lines in one go. This upscaling can occur in dvd players or in larger screen TV sets with progressive scan.

Just in case people are confused about LCD vs plasma vs CRT (older sets):

CRT- a good quality set (eg Sony /Panasonic) in my opinion offers a better picture in S.D. (standard definition) than plasma/LCD, and the black levels look much better.
(My old Sony 36inch CRT 100hz is far better than my bedrrom 2nd set: Sony LCD HDtv 26inch on SD pictures such as freeview/DVD in SD). You can now buy HD ready CRT but screen sizes now tend to be 32" or less. Advantage- price,less power than plasma (can use much higher power although latest new panasonic screens are better) but disadvantage depth/weight/ convergence problems with larger screens.

LCD- these are lighter in weight, not very deep, take less power than plasma (hence cooler). The big problem is poor black levels (i.e. if you view darker scenes they look grey rather than black because of the backlight nature of LCD). They can go to 46inch size and prices are comming down all the time. The other problem is motion blur on fast moving objects being displayed on the screen and the blocky appearance on SD lower resolution programs such as freeview compared to a crt screen.

Plasma screens start from 37inch upwards (so unable to buy smaller screens unlike LCD), they are cheaper than large screen LCD (but difference is getting smaller). In my opinion better picture quality than LCD, with better black levels and less motion blur. They can get much warmer and often internal fans can be noisy. (Newer 42/50inch plasma from panasonic are much quieter and I read new models generate less heat and may not have fans).

I must say that on a properly set up plasma or LCD HD ready large screen (42" or 50") with a HD input looks stunning. My friend has the latest panasonic 42" PX60 HD ready plasma and I think that DVD (SD) via component input look better than a large screen crt.

The future? Some companies are trying to kill off plasma/crt (Sony is only producing LCD or smaller size crt). Samsung have introduced a crt tube which is not as deep. I suspect the driving force will be the price of HD DVD/blue ray dvds and players, followed by cheaper subs for slyHD, and cable-HD when NThell get around to it (TW has already started). There are test signals (HD) in London/midlands for freeview by the BBC but expect to wait a really long time before this rolls out to freeview in general.

New technologies such as SED (years away yet) may make plasma /lcd obsolete in maybe 5-10years
(Taken from AV Forums:Stuart Wright
Administrator on AV forums:

OLED - Organic Light Emitting Diode
Kodak had a considerable hand in its development.
Has an emissive layer of an organic compound.

Compared to current flat panels:
Cheaper to make
Very thin - 30% of thickness
1,000 times faster response times
CRT like black levels
Requires 25-30% less power
Potential to be flexible – hence able to roll like a drop-down screen.

SED - Surface conductor Electron emission Display
Developed by Canon and Toshiba, works on a similar principle to CRT but with each phosphor pixel having its own tiny gun.

Compared to current flat panels:
Very thin
Very fast response times
CRT like black levels
Requires 30-50% less power.

FLCD - Ferroelectric Liquid Crystal Display
Like LCD but pixels are toggled on and off with tiny burst of power rather than requiring constant power to illuminate.

Compared to current flat panels:
Cheaper to make
1,000 times faster response times
Requires 75% less power.
Wide viewing angles)-

The above are not available and are at the research stage.