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anti-aliasing (AA)

The compensation of interference caused by aliasing is called antialiasing. Since aliasing is caused by interference and distortion of high frequency components, antialiasing filters out these frequency components by prefiltering. The input signals are therefore limited in their bandwidth before signal processing. In electronic signal processing, this is done by antialiasing filters( AAF), which are low-pass filters that limit the frequency range of the signal according to the sampling theorem.

In optical image capture, this is done by blur filters, and in image processing by software that calculates color gradients, background colors, and edges and smooths them so that color transitions appear continuous and the edges of fonts, edges, and curves appear smooth.

Line with square pixels in aliased and anti-aliased representation

Line with square pixels in aliased and anti-aliased representation

In image processing, a distinction is made between temporal and spatial antialiasing, i.e. spatial. In this method, the color values are calculated from the edges of the polygons and these are interpolated with the color values of the surroundings, which results in smoothing. Another method calculates the graphics internally with a higher resolution, renders the graphics and calculates the resolution down again. This process may well be performed several times.

In the antialiasing of edges and contours, edge aliasing, the edge shapes are represented by polygons and lines. To achieve a smooth transition of the edge with the graphics, the polygon values can be interpolated.

Informations:
Englisch: anti-aliasing - AA
Updated at: 04.08.2011
#Words: 228
Links: interference (I), aliasing, distortion, high frequency (HF), bandwidth (BW)
Translations: DE
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