Understanding Resolution & Video

Simply defined, "resolution" refers to the number of lines of picture image displayed on screen. The greater the resolution, the greater the picture quality. For example, a standard TV signal displayed on a standard TV set consists of 480 lines of resolution. HDTV (high-definition) signals, on the other hand, contain more than 700 lines -- hence their superior quality.

But, of course, there's much more to know about "resolution." And the more you know, the smarter your final choice will be when selecting the right home-theater projector for you.

"Fixed" Resolution

Portable home-theater LCD and DLP projectors both come in different "fixed" resolutions. That is, not every projector has the same resolution as every other. And a projector's fixed resolution rarely matches the exact resolution of the incoming signal. Therefore, the projector must first resize the signal's image internally, through shrinking or stretching, to map it onto its own fixed-resolution LCD or DLP panel.

Varieties of Fixed-Resolution Projector Panels

• VGA (obsolete)
• SVGA = 800 x 600 pixels
• XGA = 1024 x 768 pixels
• SXGA = 1280 x 1024 pixels (uncommon)

These terms represent the various fixed resolutions of a projector's internal panel, onto which an incoming signal must first be mapped before it can then be projected. SVGA and XGA are currently the most common resolutions in the marketplace. SVGA, being of lower resolution (800 pixels wide x 600 pixels high), is less expensive than XGA (1024 x 768), but doesn't provide sufficient resolution to do justice to HDTV signals.

Are you with us so far?

Example: Suppose you have an XGA projector with an 800 x 600 incoming signal from a video source. The incoming image will need to be stretched to match the panel's fixed resolution of 1024 x 768 pixels. A mathematical algorithm is used to add/interpolate pixels within the expanded image, so that the density of pixels will remain the same as in the original signal, thus avoiding what otherwise would be a less dense and therefore blotchy picture.