R gamma

Usage
r_gamma controls how bright the screen is drawn. Some graphics cards do not properly use this setting for screen shots. This might also depend on whether the display mode of the Tremulous client is "windowed" or "full screen".

The standard gamma setting that the default 1.1.0 maps should be played with is something from 1.4 to 1.7 so just type "/r_gamma 1.7" in the console if you think that the map you're currently playing (e.g. Tremor) is too dark. It's best to make a Bind with two or three different gamma values to quickly switch while playing.

"Gamma" does not refer to brightness as you would imagine when adjusting the brightness of your display device. When you increase the brightness, a black shade would become grey and a near white shade would become white. Everything is just elevated in brightness. But when you increase the gamma, black stays black and white stays white. All brightness shades in between full bright and full dark, however, are changed. The tones in the middle between full bright and full dark are changed the most. Think about a line that is bent in the middle so that it becomes a curve. That is exactly what happens.

Some background on gamma: Most people do not know that all common display devices do not show the colors with a linear gamma. Instead, the gamma is too low, meaning that the colors are too dark. The reasons for this are historical and can be found on the Web. For the sake of consistency, this behavior has been kept this way even in modern flat screen displays. The digital values range from 0 to 255 whereas 0 means black and 255 means full bright. But to achieve exactly the middle brightness between 0 and 255, you can't use 128 but would instead have to use something like 175. Every picture on the Web that looks properly on a normal display device does not have linear gamma. They are all too bright - to accommodate the display devices which display everything with a too dark gamma.

Graphics software (just like the Tremulous client) usually calculates with linear gamma. This means that the output is too dark for common display devices. Hence it has to be brightened. And this is why Tremulous has the r_gamma variable.