With Plasma, LCD & LED displays, non-uniform use of pixels, such as prolonged display of non-moving images like HUD bars while gaming, or certain broadcasts with channel logo and tickers, can create a permanent ghost-like image of these objects and reduce the displays image quality. This is due to the phosphor compounds which emit light to produce images.
Uneven usage results in uneven light output over time and in many cases can create a ghost image of previous content. Even if ghost images are not recognizable, the effects of screen burn are an immediate and continual degradation of image quality.
The length of time required for noticeable screen burn to develop varies due to many factors, ranging from the quality of the phosphors employed, to the degree of non-uniformity of sub-pixel usage. It can take as little as a few hours or a few weeks for noticeable ghosting to set in, especially if the screen displays a certain image (example: a menu bar at the top or bottom of the screen) constantly, and displays it continually over time.