Description
Gamma affects the difference of colour values between black and white. Black will stay black (unlike brightness which will make black grey if increased) but the colour range will change as you change the values. For example if you increase gamma the middle value of a colour will move down giving more bright levels than dark therefore increasing the overall brightness of the screen and vice versa. This option does not affect artwork or MAME's menus.
Example
mame <gamename> -gamma 1.5
Command Format
<gamename> -gamma <decimal number> where the number is the amount gamma is applied . The example will give brighter colours if used.
MAME's Default Setting
1.0 (Min 0.1 / Max 3.0)