Aliasing

What is aliasing?
Aliasing is an effect which means that different signals can no longer be distinguished from one another during scanning. Aliasing is characterized by changing the output from the original signal because resampling or interpolation resulted in lower resolution in images, lower frame rate for video, or lower wave resolution in audio. Anti-aliasing filters can be used to correct this problem.

In a digital image, aliasing manifests itself as a moiré pattern or rippling effect. This spatial aliasing in the pattern of the image makes it appear as if it has waves or ripples emanating from a particular section. This happens because the pixelation of the image is poor; When our eyes interpolate these pixels, they just don't look right.

Aliasing can also occur in videos, where it is known as temporary aliasing, as it is caused by the frequency of the frames rather than the pixelation of the image. Because of the limited frame rate, a fast moving object like a wheel looks like it is turning backwards or too slowly. this is called the wagon wheel effect. This is determined by the frame rate of the camera and can be avoided by using temporary aliasing reduction filters while filming.

In audio, aliasing is the result of a sampling sequence with lower resolution, which manifests itself in poor sound quality and static quality. This occurs when audio is sampled at a lower resolution than the original recording. When the sinusoidal audio wave is converted to a digital wave using a lower resolution sample, only some specific points of the wave are taken as data. This results in a wave at a lower frequency than the original, resulting in a loss of data and audio quality.