dithering

dithering

Simulating more colors and shades in a palette. In a monochrome system that displays or prints only black and white, shades of grays can be simulated by creating varying patterns of black dots. This is how halftones are created in a monochrome printer.

In color systems, additional colors can be simulated by varying patterns of dots of existing colors. Dithering cannot produce the exact same results as having the necessary color depth (levels of gray or colors), but it can make shaded drawings and photographs appear much more realistic.

Dithering is also used to create a wide variety of patterns for use as backgrounds, fills and shading as well as for creating anti-aliasing effects.

Dithering a Color Image

When there aren't enough colors in a display system to render an image properly, an infinite palette can be created by dithering. Quite often, a 24-bit color image is dithered to 256 colors. The right side is a magnification of the white box on the left.

Dithering Text

Text is also dithered. Notice how much softer the word DATABASE is at the top of this example, compared with the undithered word below it. The magnified view shows where lighter blue pixels filled in for the curves. When dithering is performed against the edges of an image, it is called "anti-aliasing."

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(data, algorithm)

dithering - 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.