from
The Free On-line Dictionary of Computing (8 July 2008)
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
(http://cs.cmu.edu/afs/cs.cmu.edu/user/rwb/www/gamma.html).
["Digital Imaging in C and the World Wide Web", W. David
Schwaderer (http://itknowledge.com/)].
(1999-02-01)