Aliasing

:This article applies to signal processing, including computer graphics. For uses in computer programming, please refer to aliasing (computing).

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In statistics, signal processing, and related disciplines, aliasing is an effect that causes different continuous signals to become indistinguishable (or aliases of one another) when sampled. When this happens, the original signal cannot be uniquely reconstructed from the sampled signal. Aliasing can take place either in time, temporal aliasing, or in space, spatial aliasing.

Related Topics:
Statistics - Signal processing - Sampled - Temporal aliasing - Spatial aliasing

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Aliasing is a major concern in the digital-to-analog conversion of video and audio signals: improper sampling of the analog signal will cause high-frequency components to be aliased with genuine low-frequency ones, and be incorrectly reconstructed as such. To prevent this problem, the signals must be appropriately filtered, before sampling.

Related Topics:
Digital-to-analog conversion - Video - Audio - Analog signal - Frequency - Reconstructed - Filtered

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It is also a major concern in digital imaging and computer graphics, where it may give rise to moiré patterns (when the original image is finely textured) or jagged outlines (when the original has sharp contrasting edges, e.g. screen fonts). Anti-aliasing techniques are used to reduce such artifacts.

Related Topics:
Digital imaging - Computer graphics - Moiré pattern - Image - Screen fonts - Anti-aliasing - Artifact

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