Glossary A–ZLetter G
Gamma
Gamma describes how a screen converts the brightness values of a signal into the brightness it actually emits.
The relationship is not linear but follows a curve. The curve is chosen so that the gradations match the way the eye perceives brightness.
Images and videos are created with a particular gamma curve, for office monitors and the web usually with a value of around 2.2. If the screen's gamma matches it, shadows and mid-tones look as intended. On LED walls, gamma is set in the controller and has a strong influence on how dark areas and gradients appear.
An incorrectly set gamma makes images look either flat and grey or too dark and harsh; details in the shadows are lost. On video walls made of several screens, a different gamma shows up as a jump in brightness between devices. Operators should run the screens of one surface with the same picture settings and, after replacing a device, match the settings rather than only adjusting the brightness.