Screen gain

Screen gain compares how much light a projection surface reflects straight back toward the viewer versus a standard flat white reference, which is rated at 1.0 gain. A screen rated above 1.0, sometimes called a high-gain screen, concentrates reflected light more narrowly back toward the seating area, making the image look brighter from directly in front but dimmer for anyone seated well off to the side.

Low-gain or gray screens, often rated under 1.0, spread light more evenly across a wider viewing cone but sacrifice some peak brightness, which can be a reasonable trade in a very bright projector setup or a room where several viewers sit at different angles. ALR screens use directional gain in a related but more targeted way, aimed specifically at rejecting light from certain angles.

A common mistake is choosing a high-gain screen to compensate for a dim projector, without realizing it narrows the usable seating area and can create a visible hot spot in the middle of the image. Matching screen gain to both projector brightness and the actual seating layout, rather than gain alone, gives a more even and predictable result.