“aliasing”的概念、定义、翻译、参考文献-科学参考

aliasing

Astronomy

A phenomenon in which a digitized signal is observed to contain spurious low-frequency components. These occur if the original signal is sampled at a rate insufficient to record the highest frequencies present (undersampling).

Computer

A distorting effect caused by sampling an image at too low a rate. When a signal is undersampled, high-frequency components cannot be distinguished from lower-frequency components. Thus the higher frequencies assume the alias (or false identity) of the lower frequencies. Some common computer-graphics artefacts due to aliasing are jagged lines, small objects missing from a scene, and jerky motion. Aliasing effects can be removed or subdued by anti-aliasing. Fine detail, such as mesh curtains, can be totally lost or distorted without anti-aliasing. Aliasing effects are even more prominent in animated images.

Electronics and Electrical Engineering

A distorting effect that occurs when an analogue signal f(t) is sampled digitally at a sampling frequency less than twice the signal frequency (see Nyquist rate): a signal f(t′) is retrieved from the sampled information that differs from the original input signal. The retrieved signal – the alias signal – has a frequency that corresponds to the harmonics of the high-frequency components of f(t). Anti-aliasing is any action taken to reduce or remove aliasing effects. See also anti-aliasing filter.

Geology and Earth Sciences

A distortion in the frequency of sampled data produced by insufficient sampling per wavelength, which can result in spurious frequencies. When the sampling rate is too low to represent the wave-form accurately, then aliasing will occur. To avoid aliasing, the sampling frequency should be at least twice that of the highest-frequency component contained within the sampled wave-form. Alternatively, an anti-alias filter can be applied, which removes frequency components above the Nyquist frequency.

单词	aliasing
释义	aliasing Astronomy A phenomenon in which a digitized signal is observed to contain spurious low-frequency components. These occur if the original signal is sampled at a rate insufficient to record the highest frequencies present (undersampling). Computer A distorting effect caused by sampling an image at too low a rate. When a signal is undersampled, high-frequency components cannot be distinguished from lower-frequency components. Thus the higher frequencies assume the alias (or false identity) of the lower frequencies. Some common computer-graphics artefacts due to aliasing are jagged lines, small objects missing from a scene, and jerky motion. Aliasing effects can be removed or subdued by anti-aliasing. Fine detail, such as mesh curtains, can be totally lost or distorted without anti-aliasing. Aliasing effects are even more prominent in animated images. Electronics and Electrical Engineering A distorting effect that occurs when an analogue signal f(t) is sampled digitally at a sampling frequency less than twice the signal frequency (see Nyquist rate): a signal f(t′) is retrieved from the sampled information that differs from the original input signal. The retrieved signal – the alias signal – has a frequency that corresponds to the harmonics of the high-frequency components of f(t). Anti-aliasing is any action taken to reduce or remove aliasing effects. See also anti-aliasing filter. Geology and Earth Sciences A distortion in the frequency of sampled data produced by insufficient sampling per wavelength, which can result in spurious frequencies. When the sampling rate is too low to represent the wave-form accurately, then aliasing will occur. To avoid aliasing, the sampling frequency should be at least twice that of the highest-frequency component contained within the sampled wave-form. Alternatively, an anti-alias filter can be applied, which removes frequency components above the Nyquist frequency.
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