dithering

data, algorithm A technique used in quantisation processes

such as graphics and audio to reduce or remove the

correlation between noise and signal.

Dithering is used in computer graphics to create additional

colors and shades from an existing palette by interspersing

pixels of different colours. On a monochrome display,

areas of grey are created by varying the proportion of black

and white pixels. In colour displays and printers, colours

and textures are created by varying the proportions of

existing colours. The different colours can either be

distributed randomly or regularly. The higher the

resolution of the display, the smoother the dithered colour

will appear to the eye.

Dithering doesn't reduce resolution. There are three types:

regular dithering which uses a very regular predefined

pattern; random dither where the pattern is a random noise;

and pseudo random dither which uses a very large, very

regular, predefined pattern.

Dithering is used to create patterns for use as backgrounds,

fills and shading, as well as for creating halftones for

printing. When used for printing is it very sensitive to

paper properties. Dithering can be combined with

rasterising. It is not related to anti-aliasing.

(2003-07-20)