by Bill Elliott, HD Director of Photography

So what's all the hype? Can you really see a difference? The answer is a resounding yes! The pixels in HDTV sets are smaller, and spaced closer together, than those used in analog televisions. There can be (4 1/2) HDTV pixels in the same space that a single analog pixel requires.

The result is that High-Definition-Television can display at least 4.5 times more detail than analog TV. Not only are the pixels smaller, but there are more lines of resolution in both 1080i interlaced and 720p progressive HDTV standards.

The 720p standard displays a picture made up of 720 lines of resolution scanned progressively. That is, all 720 lines are scanned in sequence from line 1 to line 720 to make up one frame of the image. Many viewers, including those in the computer world, prefer the 720p format because its progressive scanning enables it to reproduce fast-moving action and graphics without blurring the image. Thus, 720p is said to have better "temporal" resolution. The monitor that you use with your computer is a progressive scanning display.

1080i (1080 interlaced scan lines) displays more lines and thus delivers more information than 720p. This results in better "spatial resolution" - producing sharper pictures when the image is "still" or have little motion. Manufacturers have generally preferred the Interlaced format because more lines of resolution can be delivered with less bandwidth, resulting in lower costs.

Both sides in this interlaced - progressive debate are dug-in, with ardent supporters and aggressive detractors abounding on each side. But which is the better system is subjective. It really comes down to which picture you like the most. But, in the end, chances are that the HDTV picture that you watch at home could have originated as either 1080i or 720p.

Television networks have individually selected the particular DTV format they wish to transmit. For instance, ABC uses 720p, while CBS transmits in 1080i, and FOX has elected to transmit only SDTV (480-p). This is the one reason that, when choosing your new HDTV set, you should look for a set that can receive and display either signal. If not, your set will undoubtedly convert one signal to the other for playback on your screen.