OTHER TECH

Getting the Picture Plasma image quality has come a long way since the first panels were introduced, but experts generally agree that video on plasma screens still doesn't look as good as on the best tube-based high-definition TVs. "Today's plasma displays are seriously better than they were two years ago, but there are still some issues," explains video consultant Joe Kane, co-founder of the Imaging Science Foundation and producer of the forthcoming calibration DVD Digital Video Essentials.

"The major problem," he says, "is lack of resolution in the grayscale. In other words, there are too few increments, or steps, of gray to produce a smooth, noiseless transition between black and white. People in the TV manufacturing industry tell me that it will be at least three years before we'll see the problem solved."

The video signal processors inside plasma TVs have to do a lot of work to match the resolution of the incoming programs - in either a standard or high-definition format - to the panel's fixed number of pixels (its native resolution). In most cases the signal has to be de-interlaced and converted for display, a process known as scaling.

Since the resolution of standard TV is fairly low, it needs to be scaled up to fit the pixel count in plasma sets. Material in the most commonly used HDTV format, 1080i (interlaced) - which has a 1,920 x 1,080 pixel count - must be scaled down to fit the native resolution even of high-end plasma sets, which sacrifices some picture detail. The other high-definition format, 720p (progressive), requires a panel with at least 1,280 x 720 pixels to avoid reducing image quality. But no video signal format has a resolution of 1,024 x 1,024 pixels, so a panel with that pixel count needs to have all incoming video scaled.

Scaling isn't a problem as long as the processor does a good job, and some built-in scalers work fine. Still, people who want the best video performance often attach outboard processors to scale and otherwise process the video signal before it reaches the plasma panel. Outboard processors are available from a number of companies, including Faroudja, Runco, and Vidikron.