How to choose the gain of the projection screen?

Projection screens are used in movies, offices, home theaters, large conferences and other occasions to display images and video files. Divided into many specifications and sizes.

The selection of projection screens in different spaces is also different. For example, when there are many people watching or viewing horizontally, it is better to choose a screen with a wide viewing angle and low gain. The screen helps to improve the contrast of the screen, increase the gray scale of the image, make the color vivid, and increase the visibility of the image.

(Pic from vividstorm)


Gain is a digital representation of the inherent reflection characteristics of the curtain material (brightness at various angles). Project a certain amount of light onto a completely diffuse scattering surface (that is, a reflective surface with the same reflectivity in the up, down, left, and right directions of 180 degrees), and the reflection brightness at this time is set to 1. Then under the same conditions, the same light is projected in the vertical direction of the screen, and the brightness of the center point and each point on the same arc is measured. The ratio of this brightness to the brightness of completely diffuse scattering is called the gain of the screen.

Half gain is an important indicator to measure the brightness of the screen. The center of the screen is the brightest point of the screen when viewed perpendicular to the direction of the screen. When the viewer looks away from the central axis of the screen, the gain when the screen brightness is reduced to half of the maximum brightness is the half gain. In addition, the viewing angle when the gain of the screen is reduced to half is called the half-gain angle, and the half-gain angle is also an important indicator for measuring screen technology. The larger the half-gain angle, the more content on the screen we can clearly see.

The effect of screen gain on the image: the image presented by the screen without gain is relatively peaceful and faithful, but it is easily affected by the environment and external light. Gained screens, on the other hand, deliver bright, richly layered, colorful images that are less affected by ambient and external light. However, there is a special inverse relationship between the gain of the screen and the viewing angle of the screen, that is, the higher the gain, the smaller the viewing angle will be. If the gain is too high (the half-gain angle is too small), it will cause the effect of being bright in the middle of the picture and dark in the four corners, and the high-brightness part will appear saturated without layering. Because the energy is too concentrated, only one or two seats in the horizontal direction can see the bright, bright picture. Therefore, according to different applications, the projection screen should be properly selected. The higher the gain of the screen, the better.


(Pic from vividstorm)