Ten HDTV Myths

Photograph: Chip Simons
Plasma TV sets start out bright and beautiful, but burn out to an early death. Every single high-definition television program looks equally crisp and gorgeous. The higher resolution of a 1080p high-def set means that your shows and DVDs will always look better than on a more ordinary 720p set.

Are these gospel truths about HDTV? Nope. Just a sampling of the many popular factoids, half-truths, and myths that can make choosing and enjoying a high-def television set complicated and confusing--and in some cases, needlessly expensive.

To help dispel these myths, we consulted an A-team of HDTV experts. The challenge: Identify and debunk troublesome, costly, and all-too-prevalent misconceptions about high-definition TV--from the basics of broadcasting to the arcane secrets of hardware. We lay out the facts you'll need to have at your disposal in order to make the right decisions. Armed with this information, you'll know just what to expect when you take the HDTV plunge.

"An HD set is all you need to get high-def programs."

In our dreams! To experience the vibrant images and the Dolby 5.1 sound of true high-definition TV, you need several things--and an HD-ready set (a display that can accept HD-format input and display it at a minimum of 720 lines of progressive-scan or noninterlaced video) is just one of them.

First, a show needs to be shot in high definition, and that may not be the case, even when a show claims that it is. Bjorn Dybdahl, owner of Bjorn's, a high-end audio-video store in San Antonio, Texas, says that he's seen many high-def sports broadcasts shown partly in standard definition because the producer is using some non-HD cameras in its coverage. And although TNT's digital channel presents Law & Order reruns in high definition, early episodes weren't shot in HD; as a result, in those episodes, you see a 4:3 standard-def show that is stretched and scaled up to high-def size. It doesn't look great.

Second, the program must be transmitted in high def by a station that you can receive either over the air or from your cable or satellite provider. ("Shown in high definition where available" doesn't mean it's available to you.)

Third, you need an HD receiver to process the signal. A set that has a built-in ATSC digital tuner can display over-the-air HD broadcasts with nothing more than a good antenna. ATSC, which stands for Advanced Television Systems Committee, is the group that defined the 18 formats of the coming digital TV system, only 6 of which are considered high definition. (And by the way, there is no such thing as an HD antenna--there are just antennas.) If your HDTV set comes with picture-in-picture, you won't get high-def-picture-in-high-def-picture unless your set comes with two ATSC tuners.

An HD-ready set lacks such a tuner, so you'll need either a set-top box with a tuner, or an HD box from your cable or satellite service. Regardless of the box you get, you need to make sure that you're feeding its digital output into your HD-ready set. "A lot of people will get an HD-ready set [and] an HD cable box, but they will use the analog feed from the HD box," says Jeff Cove, Panasonic's vice president for technology and alliances.

Finally, you must tune your HDTV set to a high-definition channel showing actual HD content. Picking up the analog transmission from your local affiliate on your high-def cable box won't result in delivery of a show in HD.

"The bigger your HDTV set, the better it will look."

Bigger isn't better if you are seated so close to the set that you can see every pixel or line of resolution. Generally, you don't want to sit closer to a 720p HDTV than twice the length of the screen diagonal.

On the other hand, if you sit too far away from a high-resolution TV, its special benefits may disappear. "For an awful lot of viewing, what limits the resolution is the human eye," says Larry Web-er, president-elect of the Society for Information Display, a group of display industry pros. At a distance of 10 feet from the screen, the eye can't detect pixels smaller than 1 millimeter; so if you look at a 37-inch set from that far away, you won't notice significant difference between a high-definition image and a standard-def image.

Content also affects perceived image quality. Digital TVs are fixed-pixel displays--the screen resolution is hard-wired, so content has to be scaled, or adjusted, to fit the screen resolution. Not surprisingly, most television content is most attractive when displayed at its native resolution. That's why today's DVD movies, which reproduce the original film at 480 lines of progressive-scan video, may look better on an Enhanced Definition TV than on an HDTV: EDTV has the same screen resolution (480p) that DVDs have, while HDTV must scale the number of lines to 720p or 1080p (depending on the set), usually via software interpolation.

Conversely, to display HD programming, an EDTV has to eliminate lines of content (once again, usually by software interpolation), and on larger sets the resulting quality loss may be quite obvious.

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