dithering


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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.

dithering

Causing a displayed or printed image to appear more photographic by inserting shades of gray or color. Dithering simulates more colors and shades in a palette than actually exist.

While dithering cannot produce the identical results as having sufficient levels of gray or colors in the graphics display system (the color depth), it can make shaded drawings and photographs appear extremely realistic. See color depth, 24-bit color and halftone.

Dithering is also widely used to smooth curves and diagonals (see anti-aliasing).


Dithering a Color Image
An infinite palette of colors can be created by using varying shades in adjacent pixels. The right side is a magnification of the left.







Text Is Also Dithered
At the top of this example, the dithered word DATABASE is softer than the undithered word below. The magnified view shows the lighter blue pixels filling in the curves. Dithering on curves and diagonals is called "anti-aliasing."







More Shades Than You Think
At a quick glance, this Android logo appears to be solid green, white and black. However, the magnified view of one of the antennas shows otherwise. See GIF.
References in periodicals archive ?
Theory of nonsubtractive dithering has been discussed in the paper from the general quantization theory point of view using characteristic functions.
Because of the critical importance of delaying surface oxidation, which initiates dithering failure mechanisms, counter face selection becomes absolutely critical.
The DS1090 reduces system-level electromagnetic interference (EMI) by dithering the master oscillator frequency to reduce peak spectral energy at the fundamental and harmonic clock frequencies.
Media reports on General Synod's decision to defer the vote on the issue of same-sex blessings brought to mind a collection of dithering old traditionalists caught in a time-warp.
I think there has been too much dithering from the present government.
All of which, she writes, will likely factor into the federal government's dithering over whether or not homosexuals should be allowed to marry.
The SL705S supports true SVGA resolution and is compatible with digital-compression dithering technology up to SXGA resolution.
Nicholas, a "young man of impetuous temper and of little or no experience," loses his father and has to look out for his dithering mother and lovely sister Kate.
Now dithering to beat the band, Howard talks himself into a big ticket for littering.
provided that productive discussion and not further dithering is the objective.
This whole episode of reforming the Barnett formula and a referendum on devolving income tax powers to Wales is another case of Labour dithering or procrastinating; the same old Labour Party.