anti-aliasing

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anti-aliasing

(graphics)
A technique used on a grey-scale or colour bitmap display to make diagonal edges appear smoother by setting pixels near the edge to intermediate colours according to where the edge crosses them.

The most common example is black characters on a white background. Without anti-aliasing, diagonal edges appear jagged, like staircases, which may be noticeable on a low resolution display. If the display can show intermediate greys then anti-aliasing can be applied. A pixel will be black if it is completely within the black area, or white if it is completely outside the black area, or an intermediate shade of grey according to the proportions of it which overlap the black and white areas. The technique works similarly with other foreground and background colours.

"Aliasing" refers to the fact that many points (which would differ in the real image) are mapped or "aliased" to the same pixel (with a single value) in the digital representation.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

anti-aliasing

(1) Smoothing the jagged appearance of diagonal lines in a bitmapped image. The pixels that surround the edges of the line are changed to varying shades of gray or color in order to blend the sharp edge into the background. This technique is also called "dithering," but is usually known as anti-aliasing when applied to diagonal and curved lines.

(2) Smoothing a distorted signal by applying various techniques that add data or filter out unwanted noise.


Anti-aliasing
This teapot from the University of Utah was a famous first example of anti-aliasing applied to images. (Images courtesy of Computer Sciences Department, University of Utah.)


Anti-aliasing
This teapot from the University of Utah was a famous first example of anti-aliasing applied to images. (Images courtesy of Computer Sciences Department, University of Utah.)
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Due to build in lowpass antialias acausal filter in used seismometers REFTEK false signals can be seen in the records of explosion, namely for records in small epicentral distances, i.e.
Therefore, the ARB files require only four times oversampling compared to most other systems which rely on higher oversampling rates, requiring increased file sizes and switched banks of antialias filters.
Moreover, it is possible to use charge domain sampling to leverage the inherent benefits of including of a built-in antialias filter into the sampler, robustness to jitter, and the ability to vary the resulting filter notches by simply varying the integration period.
Figure 2 shows the schematic of the cross feedback control system, where [g.sub.b](s), [g.sub.cr](s), and [g.sub.f](s) are the transfer functions of the basic controller (such as a PID controller), the cross feedback controller, and the antialias filter, respectively.
Considering the bandwidths of interest of the current loop and the position loop of the MSFW and the simplicity of the realization, second-order antialias filters are introduced into both the displacement and current AD sampling of the MSFW system, whose transfer function is given as
A stand-alone digital filter requires an ADC with an associated antialias filter, a DSP chip, and a PROM or software driver.
613-749-9241 48-kHz bandwith, 75-kHz fixed antialias