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Television: Acronyms, Specifications, And Geometry

Royal Van HornPhi Delta Kappan; Bloomington Vol. 87, Iss. 8,  (Apr 2006): 629-630.

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IF A NEW high-tech television is in your future, you might want to bone up on your geometry. Let me explain. In the early days of television, the National Television Standards Commission (NTSC) set the aspect ratio (width divided by height) of the television screen at 4 by 3 or 1.33. Today, you can still buy 4-by-3 sets, or you can buy a widescreen set with an aspect ratio of 16 by 9 or 1.78. Most television stations or channels still broadcast in a 4-by-3 format, so a television set with that aspect ratio makes sense.

However, if you watch a lot of movies or programs on high-definition, cable, or satellite channels, a number of these will be widescreen productions. Now here is the downside of this geometry. If you watch a 16-by-9 program on a 4-by-3 set, the screen is "letter boxed" - meaning it has black bars on the top and bottom of the screen (Figure 1, top). If you watch a 4-by-3 program on a 16-by-9 set, the image is "pillar boxed" - meaning there are black bars on the left and right of the screen (Figure 1, bottom). In either case, a sizable portion of the television screen is unused. (I should mention here that Europe and other parts of the world do not use the NTSC standard, so some of what follows does not apply to readers outside the U.S.)

There are several "work arounds" for letter boxing and pillar boxing. Most widescreen sets (16 by 9) have aspect adjustments. The most common aspect adjustment is to stretch - or widen - a 4-by-3 program to fill the widescreen. I suppose you could get used to this, but it sure makes people look plump. Going in the opposite direction, some widescreen DVD movies are also...