The 'gama' Resources
When the user presses the Option key while clicking the Options button in the
Monitors control panel, a list of gamma tables is displayed (the Figure in the
gamma table to correct for the fact that the intensity of each color on a
video display is not linearly proportional to the intensity of the electron beam;
in other words, the gamma table helps the video driver to provide the most
accurate colors possible for a video display. Because the user might prefer a
nonstandard color correction, many developers of video cards provide more
than one gamma table for a given card.
To include one or more gamma tables for a video card, include in the Monitors
extension file a named resource of type 'gama' for each gamma table. The user
can select which gamma table to use with the monitor by clicking the name of
that table, or the user can select the default gamma table for that monitor by
clicking the box that appears above the gamma table. The default gamma table
for a monitor is the one listed in the 'scrn' resource. Gamma tables are
discussed in Designing Cards and Drivers for the Macintosh Family, second
description.