ASPECT RATIOS
First, the Basics
An ‘aspect ratio’ is simply the ratio of the width vs. the height of the screen. For example, the current aspect ratio standard is 4:3 (or 1.33:1), where the image is 4 units wide and 3 units tall.
3 units tall
4 units wide 
All of our ‘regular’ televisions are this aspect ratio. You have probably noticed that occasionally you’ll watch a movie that does not fill the screen vertically. This is because the movie was filmed in WIDESCREEN (letterbox), and the result is ‘black bars’ above and below the image:
Obviously, watching a movie like this does not lend itself to a truly cinematic experi- ence! This is why Runco invented the
A WIDESCREEN can be a number of aspect ratios; many movies are either 1.85:1 or 2.35:1, and HDTV is always 1.78:1 (16:9). The way we create a widescreen (or LETTERBOX) aspect ratio is to take a full 4:3 image, then ‘blank’ (or cut off) the top and bottom so the displayed image is in a widescreen format. For movies recorded in ‘letterbox’, there would be no information above and below the screen anyways, so we’re not losing any of the picture. However, if you were to watch standard tele- vision broadcast this way, you would lose some information (see next drawing).
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