Aliasing

  1. Pengenalan suatu artefak atau kesalahan dalam pengambilans ampel dari suatu sinyal periodik bila frekuensi pengambilan sampel terlalu rendah untuk menangkap sinyal dengan baik.
  2. Pada ultrasonografi Doppler, suatu artefak muncul bila kecepatan objek sampel terlalu besar bagi frekuensi Doppler untuk ditentukan oleh alat tersebut.
  3. Pada magnetic resonance imaging, artefak yang muncul bila bagian yangs edang diperiksa jatuh di luar lapangan pandang tetapi muncul di dalam lapangan pandang.
Aliasing (Wikipedia)
This article is about aliasing in signal processing, including computer graphics. For aliasing in computer programming, see aliasing (computing).
Properly sampled image of a brick wall (requires screen of sufficient resolution to prevent moiré pattern)
Spatial aliasing in the form of a moiré pattern

In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable (or aliases of one another) when sampled. It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal.

Aliasing can occur in signals sampled in time, for instance digital audio, and is referred to as temporal aliasing. Aliasing can also occur in spatially sampled signals, for instance moiré patterns in digital images. Aliasing in spatially sampled signals is called spatial aliasing.

Aliasing is generally avoided by applying low pass filters- anti-aliasing filters to the analog signal before sampling.