How is the performance of a projection screen measured?

By means of a number of measurements, we are able to make a good comparison of the performance of the screens in a specific situation. What do we measure?
 

The peak gain

The amount of light emerging perpendicular to the screen.

The half-maximum angle

At which angle is the gain 50% of the peak gain? If this angle is very small (<15º), a ‘hot spot’ is created. Strong dimming occurs towards the edges of the screen, especially with images that are not very bright. This effect is aggravated when the viewer is close to the screen.

Light output

The amount of light not absorbed by the screen.

Reflection

• The greater the reflection of the incident light, the lower the contrast.
• The screen brightness ratio is the difference between the brightest and darkest parts of the screen. 
• Dark areas are illuminated by stray light: the light that falls on the rear and on the front of the screen. The greater the stray light, the more details are lost in the darker areas.