aliasing 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.

aliasing 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.