An undesirable distortion component that can arise in any digitally encoded information (sound or picture).
Distortion in the video signal which may manifest itself in different ways, depending on the type of aliasing:
• Spectral aliasing is caused by interference between two frequencies, such as the luminance and chrominance frequencies or thechrominance and field scanning frequencies. It appears as moire or herringbone patterns, straight lines that become wavy, or rainbow colors.
• Spatial aliasing is distortion that occurs because of limitations in physical resolution of the scanning process. It appears, for example, as straight diagonal lines that become stairstepped or jagged.
• Temporal aliasing is distortion resulting from information lost between line or field scans. It appears, for example, when a video camera is focused on a computer screen; the video output shows a flickering bar on the computer screen because of the lack of scan synchronization of the camera and the computer.
Defects or distortion in a television picture due to sampling limitations. Defects are commonly seen as jagged edges on diagonal lines and twinkling or brightening (beating) in picture detail.
Something other than what it appears to be. Stairsteps on what should be a smooth diagonal line are an example of spatial alias. Wagon wheels appearing to move backwards are an example of temporal alias. Aliases are cause by sampling and can be reduced or eliminated by pre-filtering, which can appear to be a blurring effect. Defects in the picture typically caused by insufficient sampling (violation of the Nyquist sampling rate) in the analog to digital conversion process or poor filtering of digital video. Defects are typically seen as jaggies on diagonal lines and twinkling or brightening in picture detail. Examples are: Temporal Aliasing — such as rotating wagon wheel spokes appearing to rotate in the reverse direction. Raster Scan Aliasing — such as sparkling or pulsing effects in sharp horizontal lines. Stair-Stepping — stepped or jagged edges in diagonal lines or the diagonal parts of a letter.[1]

Audio and video glossary. 2014.

Look at other dictionaries:

  • Aliasing — This article applies to signal processing, including computer graphics. For uses in computer programming, please refer to aliasing (computing). In statistics, signal processing, computer graphics and related disciplines, aliasing refers to an… …   Wikipedia

  • Aliasing — En estadística, procesamiento de señales, computación gráfica y disciplinas relacionadas, el aliasing es el efecto que causa que señales continuas distintas se tornen indistinguibles cuando se muestrean digitalmente. Cuando esto sucede, la señal… …   Wikipedia Español

  • Aliasing — Treppenstufen Effekt; Treppeneffekt; Stufenbildung * * * Ali|a|sing 〈[ɛılıəsıŋ] n. 15〉 1. verfälschtes Signal 2. 〈EDV〉 gezacktes Erscheinungsbild bestimmter Grafikelemente aufgrund der begrenzten Auflösungsfähigkeit des Bildschirms [engl.] * * *… …   Universal-Lexikon

  • Aliasing — Crénelage Le crénelage (ou crènelage) ou repli de spectre (Aliasing en anglais) est un phénomène qui peut se produire lors du traitement numérique d un signal, lorsque des fréquences qui ne sont pas représentées dans le signal original sont… …   Wikipédia en Français

  • Aliasing — Mit Aliasing wird in der Informatik das Vorhandensein mehrerer Bezeichner für eine Variable mit demselben Speicherort bezeichnet. Es kann hierbei, insbesondere in Verbindung mit Zeigern oder Referenzparametern von Prozeduren, zu undurchsichtigen… …   Deutsch Wikipedia

  • Aliasing — En estadística, procesamiento digital de señales y áreas afines, el aliasing es el efecto indeseable que causa que señales contínuas distintas se tornen indistinguibles cuando se les muestrea digitalmente. Cuando esto sucede, la señal original no …   Enciclopedia Universal

  • aliasing — ali·as·ing (aґle əs ing) 1. introduction of an artifact or error in sampling of a periodic signal when the sampling frequency is too low to properly capture the signal. 2. in pulsed Doppler ultrasonography, an artifact occurring when the… …   Medical dictionary

  • Aliasing — Erscheinung auf Monitoren und Druckern, die schräg oder diagonal verlaufende Linien oder Kreise in einem digitalisierten Bild betrifft. Es kommt zu gezackten oder unregelmäßig verlaufenden Rändern (Treppenstufeneffekt). Unterdrückt werden kann… …   Das Lexikon aus „Bernie's Foto-Programm"

  • aliasing — Алиасинг (Aliasing)     Искажения контура масштабируемых изображений, в том числе шрифтов, при воспроизведении их на экране низкого разрешения. В этих случаях изображения растрируются, то есть разбиваются на мелкие элементы (пикселы, или… …   Шрифтовая терминология

  • aliasing — spektrų sanklota statusas T sritis radioelektronika atitikmenys: angl. aliasing; spectral foldover vok. Spektrenüberlappung, f rus. наложение спектров, n pranc. superposition des spectres, f …   Radioelektronikos terminų žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.