dithering

(Image processing and computer graphics:)
The process of converting an image to use a very small number of predetermined pixel types, by forming patterns of these pixels. For instance, given red and blue pixels, we can generate magenta-like areas in the output image by placing red and blue pixels next to each other.

The most common type of dithering represents a black and white image with just 2 pixel types: black and white. This is useful for printing out the image.

Newspaper images are usually also printed using just black and white dots; however, the process there is an analogue (non-computerised) process known as halftoning. The results there are usually similar to ordered dithering, but with a rotated halftoning screen.

Being in a state of indecisive agitation. The OED defines dither as “to tremble, quake, quiver, thrill” and cites its earliest use as 1649, just slightly before computer graphics became important. Dithering is often applied to little old ladies trying to decide whether to go for the Earl Grey or the Oolong. It also describes a boss well when you present a suggestion to him that he’s not sure his superiors will like.

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