The Graphics Path
Tracing the path from data in memory to a dot on a screen traverses the major
parts of the Macintosh graphics system.
of three 16-bit values, one each for red, green, and blue. The resulting 48-bit
record is sufficient to specify far more colors than the human eye can discern.
becomes real.
The largest pixel value usable with system software version 7.0 is a 32-bit
direct pixel, of which the red, green, and blue components have 8 bits each,
and 8 bits are currently unused. RGB values of 24 bits can specify 16 million
colors, which the human eye can just barely distinguish.
Advances in technology don't always mean increases in complexity. The color
smaller amount of RAM to display nearly full-color images. Direct pixel
specification is inherently simpler-at the cost of additional RAM to hold the
greater information needed to specify an image, and additional machine cycles
to move it around.
The following two sections trace the steps from a user selecting a color to
sending signals to a video screen. Of necessity, these explanations are
simplified to provide an overview of the process.