true colour

graphics A system where the red, green, and blue components

of a colour are stored in display memory, as opposed to

storing logical colours and using a colour palette to

convert them to red, green, blue components.

The advantage of true colour over a palette is that it does

not restrict the range of colours which can be displayed on

screen simultaneously. For example, if eight bits are used to

store each component of each pixel then a total of 2^24

(about 17 million) different colours can be displayed at once

which would require a (very expensive) palette with 3 * 2^24

bytes (about 50 megabytes) of memory.

The disadvantage of true colour is that image transformations

which would normally be done by changing the palette must be

done to every pixel of the image which can be much slower.

Compare high colour.

(1996-03-24)