gamma correction

hardware 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.

More expensive graphics cards and workstations

(particularly those used for CAD applications) will have a

gamma correction facility.

In combination with the "white-point" gamma correction is

used to achieve precise colour matching.

Robert Berger's explanation of monitor gamma.

[\"Digital Imaging in C and the World Wide Web\", W. DavidSchwaderer ].

(1999-02-01)