artifact (redirected from ultrasound artifact)

artifact

A distortion in an image or sound caused by a limitation or malfunction in the hardware or software. Artifacts may or may not be easily detectable. Under intense inspection, one might find artifacts all the time, but a few pixels out of balance or a few milliseconds of abnormal sound often go undetected.

Analog Artifacts
In films and film-based videotape, artifacts such as blotches, scratches and flicker are commonly found, especially in older movies. Imperfections in the camera lenses and CCDs, and the silver-grain film itself, can generate "noise," which appears as tiny background specks, making the image softer. The electronic recording of analog videotapes can introduce noise as well. See noise.

Digital Artifacts
Artifacts are a natural byproduct of digital compression methods such as JPEG and MPEG, which permanently discard pixels. The greater the compression used, the more artifacts are likely, and fast motion sequences are a major contributor. As TV screens become larger, the distortions are more noticeable. In digital cameras, artifacts may arise when performing digital zoom. When analog material is converted to digital, tiny discrepancies (quantization errors) may result. See blocking artifacts, mosquito noise, feathering and quantization error.

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artefact, artifact

Cytology a structure seen in tissue after death, fixation, staining, etc., that is not normally present in the living tissue

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artifact [′ärd·ə‚fakt]

(archeology)

Any crafted object of common use that reflects the skills of humans in past cultures.

(communications)

Any component of a signal that is extraneous to the variable represented by the signal.

(histology)

A structure in a fixed cell or tissue formed by manipulation or by the reagent.

(medicine)

Noise or spurious signals that occur during various radiological imaging techniques; can reach a level where they appear in the image with as much strength as the signals produced by real objects.