OTHER TECH

4. HDTVs can only show high-def programming, so there's no reason to buy one if you only watch regular TV.

When the TV industry switched from black-and-white to color, broadcasters made sure that the new system was backward compatible - the new color signals had to be viewable on existing black-and-white sets. But people had never dealt with a switchover like that before, so there was concern that all older TVs would become obsolete overnight. Now that we're in the midst of the switch to HDTV, misinformation is again spreading like wildfire.

Marty Zanfino, director of product development at Mitsubishi, offers a couple of reasons why you might want to buy an HDTV even if you don't currently receive high-def programming. "The Federal mandate requires that HDTV broadcasting become widespread. Since most people keep big-screen TVs for at least seven to eight years, you should consider a high-def set because HDTV programming will soon become more common. And don't forget HDTVs have image-enhancement features like line doublers and pixel multipliers that help standard-definition material look better."

During the 1960s, owners of the new color TVs were never confused about what type of program they were watching - the picture was either in color or in black-and-white. But things aren't so clear-cut with HDTV, which accounts for these two other common misconceptions: "I have digital cable (or digital satellite), so I have HDTV" and "I just bought a new TV, so I know I'm seeing high-def whenever a program says 'Broadcast in HD' at the beginning."

Just because a TV set or a broadcast signal is digital doesn't mean it's high-definition. While cable and satellite services can deliver HDTV, most providers only offer between five and ten channels in high-def, using the rest of their digital capacity for traditional, standard-definition channels.

A program has to meet several criteria before it can be considered high-definition. First, it has to be filmed (or upconverted) and transmitted in high-def - thus the banner at the beginning of certain shows. Second, if you receive your high-def programming over the air or through cable, it has to be rebroadcast locally in HD. (Note that the fine print on the "Broadcast in HD" logo says "where available.") Third, your TV has to be capable of displaying 1080i (interlaced) or 720p (progressive-scan) images, which are the only high-def formats in wide use. Finally, you need to be able to receive and decode the signal using either a digital set-top box or a the digital tuner built into the TV (if it has one). And if you're using a set-top box, it has to be joined to the TV through a component-video, RGB, VGA, DVI (Digital Visual Interface), or HDMI (High Definition Multimedia Interface) connection. If any one of these four criteria isn't met, you're not watching HDTV.