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Reader Question: Upscaling?

April 17, 2006 | Author: sysadmindgs

Q: I’ve been told that plasma TVs are better at up-scaling to their native resolution than LCDs. But after reading your book I’ve learned that both technologies use fixed pixel addressing. So how can plasmas have an advantage over LCDs in up-scaling?
Joe Gabela

There’s nothing inherent in the plasma technology that gives it an advantage over LCD, but there are some other factors that could come into play. Let me tackle that from two angles.

First, you are correct that both LCD and plasma are fixed-address pixel designs. To that end, a major difference in performance will be caused by the choice of “scalar”: the chip that does the processing. As a general rule, an inexpensive scalar will do less well at upscaling than a more expensive one. Chips by Genesis, Pixelworks, and Silicon Optix are some of the leading choices.

There’s also a sneakier effect at work. Many “high-definition” plasma sets aren’t HD. Many of the 16:9 aspect ratio panels have physical resolutions of 1024 by 1024, or even 1024 by 768. The first point is that these are not 16:9 aspect ratios, so they don’t use square pixels the way that almost all LCD panels do. Next, 720p resolution requires at least 1280 by 720 pixels. These plasma panel resolutions don’t have enough vertical lines to produce this resolution, so it’s not really fair to call them HD. But we do.

What does this resolution issue have to do with your question? The fact is that having fewer pixels per row means that the plasma panels don’t have to interpolate as much new data when upscaling. As a result, there’s less opportunity to make a mistake and introduce a visible artifact. So it may well be that SD content might look better on one of these “almost HD” plasma panels than on a “true HD” display.