High Definition

Confusing? That’s part of the “joy” of buying HDTV. It’s the most complex and confusing example of consumer electronics I’ve seen in 20 years of writing about technology.

You can spend $10,000 for a flat panel, home-theater monster that covers the better part of a wall, or about one-tenth of that on an excellent 34-inch set like the one that hides in a corner cabinet in our living room when we’re not watching.

The problem: to buy wisely at any level, you’ll have to learn a lot more about the technology than you had to know to buy your last set.

The basics: High Definition sets are different from the last generation of TVs in two ways. First, they receive a digital signal, which is incompatible with traditional broadcasts but allows more information to be transmitted. This allows TV stations to provide additional channels, a better picture on existing channels, or a mix of the two, depending on the time of day.

Eventually (most likely in 2009), we’ll all have to buy digital sets or new digital tuners for our old sets.

One of the benefits of digital broadcasting is the opportunity to greatly improve the resolution of the TV image. High Definition sets use more dots of light, or pixels, to produce an image than standard TVs. Typically, TV makers refer to these as lines of resolution. Standard TV sets in the US produce 480 lines of resolution. Most true HDTVs can produce 1040 lines, although some manufacturers peddle lower-resolution sets that they market as HD.

HD broadcasts provide more detail than standard fare. They’re also more expensive to produce, which is why the selection is still relatively limited. HD sports are outrageously great. You can count the hairs on a quarterback’s beard halfway across the field with a good HDTV signal — if you’re into that kind of thing. This is one reason 99 per cent of these sets are bought by guys. Your average Meg Ryan chick flick won’t look much better in HDTV.

The first thing you’ll notice when you shop for HDTV is that the screen is likely to be a different shape. It seems shorter and wider than your current TV. This is the aspect ratio of the screen — width to the height. The standard TV screen we’ve watched since the late 1940s has a 4:3 aspect ratio. It was also the most common aspect ratio for Hollywood movies until the 1950s. Then movie directors increasingly produced films with much wider aspect ratios — 14:9, 16:9, or as extreme as 5:2. The goal was to engage our peripheral vision in the theater and evoke a greater sense of reality. Unfortunately, this soon created a disconnect between the TV and the motion pictures that increasingly became a major source of broadcast material.

One solution is to edit a widescreen movie for TV, so that it fits in the 4:3 window. Unfortunately, this means cutting off the edges of the action, or spending considerable time and money to pan the screen during edit to provide the best window onto the film image.

The other alternative is to show the movie in its original aspect ratio. Purists prefer this, but it creates black bands of unused screen at the top and bottom of a standard TV, a technique known as “letterboxing”.

Most HDTVs are so-called “widescreen” models. But they don’t necessarily have to be — high definition only requires a minimum number of scan lines.

Measure an old-fashioned, 36-inch screen and you’ll find a tube that’s 22 inches high by 28.5 inches wide, for a total screen area of 627 square inches. A 36-inch diagonal widescreen set, with 16:9 aspect ratio, provides only 576 square inches of viewing area. So any widescreen HDTV will be about 8 per cent smaller than a standard set with the same diagonal measurement.

Does the increased resolution make up for smaller screen size? That depends on your eye. LAT-WP