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Most TV screens and programming were designed using a 4:3 aspect ratio for standard-definition TV reception and viewing. However, most HDTVs are "widescreen," which use an aspect ratio of 16:9.
- Therefore, when a standard-definition program is viewed on a widescreen HDTV, the HDTV may center the image on the screen with black or gray margins (known as sidebars) on either side in order to retain the 4:3 aspect ratio. The cable box uses this same process when 4:3 content is viewed on the high-definition, 16:9 wide-screen HDTV.
What is letterboxing?
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When widescreen (16:9 aspect ratio) content is transmitted to a 4:3 TV screen, the content provider may add black margins on the top and bottom of the screen to ensure that the entire width of the picture is visible. This is known as "letterboxing."
Avoiding Burn-In
- Reduce the occurrence of sidebars by using the HD "stretch" or "zoom" settings whenever possible to fill the screen area with video. Because letterboxing is created by the content provider, letterboxed programs cannot always be completely zoomed to fill the screen.
- Avoid pausing DVDs or videos for extended periods of time.
- Turn down the screen contrast to 50 percent or less.