Editing Spatial anti-aliasing (section)

{{Short description|Minimising distortion artifacts when representing a high-resolution image at a lower resolution}}
{{More footnotes|date=January 2009}}

In [[digital signal processing]], '''spatial anti-aliasing''' is a technique for minimizing the distortion artifacts ([[aliasing]]) when representing a high-resolution image at a lower resolution. [[Anti-aliasing]] is used in [[digital photography]], [[computer graphics]], [[digital audio]], and many other applications.

Anti-aliasing means removing signal components that have a higher [[frequency]] than is able to be properly resolved by the recording (or sampling) device.  This removal is done before (re)sampling at a lower resolution. When sampling is performed without removing this part of the signal, it causes undesirable artifacts such as black-and-white noise.

In signal acquisition and audio, anti-aliasing is often done using an analog [[anti-aliasing filter]] to remove the out-of-band component of the input signal prior to sampling with an [[analog-to-digital converter]]. In digital photography, optical anti-aliasing filters made of [[birefringent]] materials smooth the signal in the spatial optical domain. The anti-aliasing filter essentially blurs the image slightly in order to reduce the resolution to or below that achievable by the digital sensor (the larger the [[pixel pitch]], the lower the achievable resolution at the sensor level).