Visual artifact

Visual artifacts (also artefacts) are anomalies apparent during visual representation as in digital graphics and other forms of imagery, especially photography and microscopy.

A screenshot of a Microsoft Windows XP application displaying a visual artifact with repeated frames.

Examples in digital graphics
A retinography. The gray spot in the center is a shadow artifact.

Occurrences in video entertainment

Many people who use their computers as a hobby experience artifacting due to a hardware or software malfunction. The cases can differ but the usual causes are:

  • Temperature issues, such as failure of cooling fan.
  • Unsuited video card drivers.
  • Drivers that have values that the graphics card is not suited with.
  • Overclocking beyond the capabilities of the particular video card.
  • Software Bugs in the application or operating system.

The differing cases of visual artifacting can also differ between scheduled task(s).

Confocal laser scanning fluorescence micrograph of thale cress anther (part of stamen). The picture shows among other things a nice red flowing collar-like structure just below the anther. However, an intact thale cress stamen does not have such collar, this is a fixation artifact: the stamen has been cut below the picture frame, and epidermis (upper layer of cells) of stamen stalk has peeled off, forming a non-characteristic structure. Photo: Heiti Paves from Tallinn University of Technology.

In microscopy

In microscopy, an artifact is an apparent structural detail that is caused by the processing of the specimen and is thus not a legitimate feature of the specimen. In light microscopy, arteficts may be produced by air bubbles trapped under the slide's cover slip.[1]

In electron microscopy, distortions may be produced in the drying out of the specimen. Staining can cause the appearance of solid chemical deposits that may be seen as structures inside the cell. Different techniques including freeze-fracturing and cell fractionation may be used to overcome the problems of artifacts.[1]

A crush artifact is an artificial elongation and distortion seen in histopathology and cytopathology studies, presumably because of iatrogenic compression of tissues. Distortion can be caused by the slightest compression of tissue and can provide difficulties in diagnosis.[2][3] It may cause chromatin to be squeezed out of nuclei.[4] Inflammatory and tumor cells are most susceptible to crush artifacts.[4]

  • Cellulose contamination, in H&E stain and polarized light
  • Cardiac muscle (bottom) with contamination from thyroid tissue (center)
  • Crush artifact from compression by forceps on the tissue sample
  • Folding artifacts (white arrows) and a crush artifact (black arrow, with cytoplasmic hypereosinophilia and nuclear pleomorphism) from a needle.
  • Tearing artifacts, such as can be caused by:
    - Microtomy with a nick or blemish in the knife edge.[5]
    - Traction of the sections.
    - Too much or too little alcohol dehydration.[5]
    - Sectioning calcified parts, which can be decalcified or removed.[5]
  • 'Formalin pigment artifacts
  • Air bubble entrapment artifacts
  • Staining artifacts by residual wax, resulting in pale areas where cellular structures are not discernible.
  • A separation artifact in top image makes the tumor look incompletely excised, but the next microtomy level (bottom image) shows a surgical margin of connective tissue.

In radiography

In projectional radiography, visual artifacts that can constitute disease mimics include jewelry, clothes and skin folds.[6]

In magnetic resonance imaging
Main article: MRI artifact

In Magnetic resonance imaging, artifacts can be classified as patient-related, signal processing-dependent or hardware (machine)-related.[7]

gollark: Well, you think wrong, as is typical.
gollark: At least it's better than Esobot.
gollark: 2 is very many, of course.
gollark: - it always inserted to position 0 in the queue, which somehow didn't break anything badly enough for me to notice- the thing which was meant to load old reminders into the queue only loaded past ones, causing unpredictable, weird behaviour
gollark: Okay, I have so, so many problems with this code.

References
  1. Kent, Michael (2000). Advanced Biology (Repr. ed.). Oxford: Oxford University Press. p. 64. ISBN 0199141959.
  2. Chatterjee, S. (September 2014). "Artefacts in histopathology". Journal of Oral and Maxillofacial Pathology. 18 (Suppl 1): S111-6. doi:10.4103/0973-029X.141346. PMC 4211218. PMID 25364159.
  3. Komanduri S, Swanson G, Keefer L, Jakate S (December 2009). "Use of a new jumbo forceps improves tissue acquisition of Barrett's esophagus surveillance biopsies". Gastrointestinal Endoscopy. 70 (6): 1072–8.e1. doi:10.1016/j.gie.2009.04.009. PMID 19595312.
  4. Chatterjee, Shailja (2014). "Artefacts in histopathology". Journal of Oral and Maxillofacial Pathology. 18 (4): 111. doi:10.4103/0973-029X.141346. ISSN 0973-029X. PMC 4211218.
  5. Taqi, SyedAhmed; Sami, SyedAbdus; Sami, LateefBegum; Zaki, SyedAhmed (2018). "A review of artifacts in histopathology". Journal of Oral and Maxillofacial Pathology. 22 (2): 279. doi:10.4103/jomfp.JOMFP_125_15. ISSN 0973-029X.
  6. Page 46 in: Michael Darby, Nicholas Maskell, Anthony Edey, Ladli Chandratreya (2012). Pocket Tutor Chest X-Ray Interpretation. JP Medical Ltd. ISBN 9781907816062.CS1 maint: multiple names: authors list (link)
  7. Erasmus, L.J.; Hurter, D.; Naude, M.; Kritzinger, H.G.; Acho, S. (2004). "A short overview of MRI artifacts". South African Journal of Radiology. 8 (2): 13. doi:10.4102/sajr.v8i2.127. ISSN 2078-6778. (CC-BY 4.0)
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