aliasing

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(n.) 1. The appearance of unwanted visual effects, known as jaggies, in digitized images. An example is the stairstep effect on raster display systems that do not have a high enough resolution to reproduce smooth diagonal lines or circles. 2. In audio sampling, a distortion-producing reflection caused by the fact that all frequency components higher than half the sampling frequency are reflected in the lower range. Aliasing creates artifacts. It can be avoided by processing the waveform to be sampled with a low-pass filter at half the sample rate before digitizing.