High definition (HD) is a term that is bandied about with gay abandon these days.

Many of us have already traded in our big, bulbous CRT televisions for slimline flat-panel LCDs or plasmas on the promise of being able to feast our eyes on HD goodness, whether from broadcasters, PC hard disks, games consoles or the new razor-sharp DVD formats. But the truth of the matter is that there's still a distinct lack of HD content available.

Not only that, but the HDTV you've just been sold may not even be compatible with the new versions of DVD – Blu-ray and HD DVD. In this feature we'll examine why the HD revolution is taking such a long time to get going and why you might want to think twice about investing in it at the moment.

Ready or not?
A little over two years ago, the European Information, Communications and Consumer Electronics Technology Industry Associations (EICTA) decided to help confused consumers by creating a special 'HD Ready' label.

The idea was that any device bearing the label needed to meet a strict set of criteria so that anyone shopping for high-definition equipment could look for the logo and be assured of a product's HD readiness. The trouble is that the original requirements set by EICTA arguably fall some way short of what you may want your HDTV to be capable of.

To qualify for the coveted HD Ready logo, a TV has to have DVI or HDMI inputs and be able to display a high-definition picture at both 1280 x 720 pixels (720p) and 1920 x 1080 pixels (1080i). Interestingly, however, the screen itself doesn't necessarily need to match either of these two resolutions pixel for pixel.

To meet EICTA's criteria, it only needs to have 720 physical horizontal lines. Which means that some so-called HD Ready TVs may have native resolutions as low as 1024 x 768 pixels, and will downscale (basically, squash) HD-resolution pictures to fit.

The full monty
In fact, resolution isnít the be-all and end-all, particularly on smaller screen sizes (32in and below). Other factors can contribute to how good an HD picture can look, such as the way the TV processes its image and how well it handles on-screen movement.

It's true, though, that the low resolution requirements of the HD Ready logo mean that a lot of TVs bearing the label may not be able to display 1080p HD material. Without getting too technical, 1080p is often described as 'true' or 'full' HD because it displays a top-resolution (1920 x 1080 pixels) image progressively (frame-by-frame), rather than 1080i, which splits each 1920 x 1080-pixel frame in half and shows the resulting half-frames in quick succession.

The upshot is that an HD Ready TV may not be ready for some types of HD content. It might be able to display the high-definition broadcasts from Sky's HD satellite service, for example, but it might not be able to cope with top-resolution video output from devices such as the Sony Playstation 3. Even if it can accept 1080p, unless your HDTV has a physical screen resolution of 1920 x 1080 pixels, it may be down-converting the picture to a lower resolution in order to do so.

Format bores
The good news is that, unless you have a stonking great TV screen (42in and above) you're unlikely to be able to tell the difference between 1080i and 1080p. And, as we've already said, resolution isn't everything. The bad news is that there's another problem that could get in the way of your viewing pleasure.

The problem arises when you turn to the new video disc formats, Blu-ray and
HD-DVD. Both formats were developed as the successor to DVD. You may have already heard them described as 'the VHS and Betamax of their day' and there's certainly some truth in that.

Just like the old videotape rivals, Blu-ray and HD-DVD effectively do exactly the same thing, but are mutually incompatible. As a consumer, it makes investing in the new technology hard, because there are few discernable advantages or disadvantages to help you make your choice.

Add to that the worry of buying into a format that ends up going the way of the Betamax video cassette and thereís already a strong argument for waiting until the market settles down.