Large displays (e.g., billboards), such as those commonly used for advertising in cities and along roads, generally have one or more pictures and/or text that are to be displayed under various light and weather conditions.  As technology has advanced and introduced new lighting devices such as the light emitting diode (LED), such advances have been applied to large displays.  An LED display is a flat panel display, which uses an array of light-emitting diodes.  A large display may be made of a single LED display or a panel of smaller LED panels.  LED panels may be conventional panels made using discrete LEDs or surface-mounted device (SMD) panels.  Most outdoor screens and some indoor screens are built around discrete LEDs, which are also known as individually mounted LEDs.  A cluster of red, green, and blue diodes is driven together to form a full-color pixel, usually square in shape.  These pixels are spaced evenly apart and are measured from center to center for absolute pixel resolution.