The Truth Behind 4:3 and 16:9 Formatting
September 21, 2000,
"There it is. Right there on the vendor's spec sheet. They say their projector has both 4:3 and 16:9 formats. It must be true, right? So how come ProjectorCentral's database lists it as having only 4:3?"
We get this question frequently. So it's time to clear up the mystery of aspect ratio formats. But in so doing, we will have to examine how some manufacturers design and market their projectors to get "both 4:3 and 16:9." And it's a story you probably won't like.
First things first...what does "aspect ratio" mean?
The term aspect ratio refers to the ratio of a picture's width to its height. If the aspect ratio of a picture were 1 to 1 (or 1:1), the width and height would be the same, and you'd have a square. Standard NTSC video has an aspect ratio of 4:3. That means for every four units of width, the picture will be three units high. HDTV standards call for an aspect ratio of 16:9, which describes a rectangle that is wider relative to its height than NTSC's 4:3.
In today's market, many projectors are being marketed with claims that they have both 4:3 and 16:9 aspect ratio formats. The question...how is this possible if the internal displays have just one or the other? And what does it mean to the consumer?
Think physical displays for a moment
Let's start with some basics. LCD (Liquid Crystal Display) projectors make an image by shining light through glass LCD panels made up of thousands of little dots called pixels. Each pixel controls the amount of colored light it will project. Depending on the resolution of the projector, the projected image is produced by 1 to 4 million pixels.
DLP projectors make an image by bouncing light off a DMD chip (Digital Micromirror Device) that is populated with thousands of tiny mirrors which are the equivalent of LCD pixels. Each mirror is electronically adjusted to control the amount of colored light it reflects.
The physical array of pixels on an LCD panel or a DMD chip is fixed. At the moment, most DMDs and LCDs have a 4:3 aspect ratio with pixel arrays of 800 x 600 (SVGA) or 1,024 x 768 (XGA). Aspect ratios of 5:4 are also available to support 1280 x 1024 (SXGA) projectors.
At the moment, the Sony VPL-VW10HT is the only digital projector that has genuine 16:9 LCD panels. The fixed pixel array on its panels is 1,366 x 768. That is native XGA vertical resolution extended horizontally into a 16:9 aspect ratio.
Now at ProjectorCentral, when you see the aspect ratio specification for any projector in our database, it is reporting the physical array of pixels that exist on the panels or the chips. And there is always only one...they can't be physically both 4:3 and 16:9 at the same time, no matter what the vendor's spec sheet claims.