* Burn-in can be caused by black bars. Filling the screen with a moving picture is the safest way to view non widescreen content on 16:9 plasma flat panel and CRT-based rear-projection displays. Leaving the black bars on for an extended period of time can cause permanent damage to the display--often called burn-in or image retention--which often isn't covered by the warranty. Both plasma and rear-projection CRT sets are particularly vulnerable to burn-in during the first 100 or so hours of use. During that time, we recommend you watch without vertical letterboxing at all, and that you avoid still images, such as paused games or television shows. After this initial period, the danger of burn-in is greatly reduced. Other easy measures to avoid burn in include: find a set or a source that produces gray bars (instead of black) to either side of the 4:3 image and/or features other ways to combat burn-in; turn contrast down to 50 percent or lower; balance your 4:3 viewing with more wide-screen material; in particular, sports and animation make good candidates for stretching. Burn-in does not affect LCD, DLP, or LCoS TVs and is much less likely to affect direct-view tube TVs.
As long as your TV or video source has the proper aspect ratio control settings, aspect ratio problems are completely avoidable. Over the next few years, as both hardware manufacturers and broadcasters transition from the older 4:3 format to wider, HDTV-friendly 16:9 widescreen, aspect ratio control will be particularly important.