Adjustments applied during the display of a digital representation of colour on a screen in order to compensate for the fact that the Cathode Ray Tubes used in computer monitors (and televisions) produce a light intensity which is not proportional to the input voltage. The light intensity is actually proportional to the input voltage raised to the inverse power of some constant, called gamma. Its value varies from one display to another, but is usually around 2.5.
Because it is more intuitive for the colour components (red, green and blue) to be varied linearly in the computer, the actual voltages sent to the monitor by the display hardware must be adjusted in order to make the colour component intensity on the screen proportional to the value stored in the computer's display memory. This process is most easily achieved by a dedicated module in the display hardware which simply scales the outputs of the display memory before sending them to the digital-to-analogue converters.