Screen gain measures how much a projection screen reflects light to the viewer compared to a reference surface, such as a standard whiteboard.
A screen with a gain of 1.0 reflects the same amount of light as a standard whiteboard, while a screen with a gain greater than 1.0 reflects more light back to the viewer than a traditional whiteboard. An increase of 1.0 means that the image with a higher gain will appear brighter than the same image on a screen with a lower gain.
Screen gain is typically measured in a dark room at the center of the screen. It's important to note that the gain of a screen can vary depending on the viewing angle; a screen with a high gain might look bright from the center but will look dim from the side.
Various factors, such as the screen's material, color, and surface texture, can affect screen gain. A screen made from a matte white material will typically have a lower gain than a screen made from a glossy white material.