Artifact (error)

In natural science and signal processing, an artifact or artefact is any error in the perception or the way any information is represented or introduced by the equipment or technique(s).
Computer science.
In computer science, digital artifacts are abnormalities introduced into digital signals because of digital signal processing.
Microscopy.
In microscopy, visual artifacts are sometimes introduced when processing samples into slide form.
Remote sensing.
Medical imaging.
In medical imaging, artifacts are wrong representations of structure of tissues. They are made by imaging techniques such as ultrasound, X-ray, CT scan, and magnetic resonance imaging (MRI). These artifacts may be caused because of the energy-tissue interaction between ultrasound and air. Physicians usually learn to recognize some of these artifacts to avoid mistaking them for actual pathology.
Radar.
Radar echoes from something causes ghost images to appear. All those echoes must be filtered in order to get the where the object is, how fast it is going and the type of object it is. It may include aircraft, and weather.