{{Short description|Anomaly in digital graphics or imagery}} [[File:Winxp estk artifact.png|thumb|A screenshot of a Microsoft Windows XP application displaying a visual artifact with repeated frames]]
'''Visual artifacts''' (also '''artefacts''') are anomalies apparent during visual representation as in digital graphics and other forms of imagery, especially photography and microscopy.
==In digital graphics== [[File:Retinography.jpg|thumb|A retinography. The gray spot in the center is a shadow artifact.]] * Image quality factors, different types of visual artifacts * Compression artifacts * Digital artifacts, visual artifacts resulting from digital image processing * Noise * Screen-door effect, also known as fixed-pattern noise (FPN), a visual artifact of digital projection technology *Ghosting (television) *Screen burn-in * Distortion * Silk screen effect * Rainbow effect * Screen tearing * Moiré pattern * Color banding
==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 (graphics 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).
==In photography== thumb|Circular artifacts caused by backscatter from raindrops These effects can occur in both analog and digital photography. * Chromatic aberration due to optical dispersion through a lens, leading to color fringes at high-contrast boundaries in a photograph ** Purple fringing * Motion blur * Near-camera reflection, visual artifacts caused by the backscatter of light by unfocused particles
==In microscopy== [[File:Anther of thale cress (Arabidopsis thaliana), an artefact.jpg|thumb|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, 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, artifacts may be produced by air bubbles trapped under the slide's cover slip.<ref name="Kent">{{cite book |last1=Kent |first1=Michael |title=Advanced Biology |date=2000 |publisher=Oxford University Press |location=Oxford |isbn=0199141959 |page=64 |edition=Repr.}}</ref>
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.<ref name="Kent"/>
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.<ref name="Chatterjee2014" /><ref>{{cite journal |vauthors=Komanduri S, Swanson G, Keefer L, Jakate S |title=Use of a new jumbo forceps improves tissue acquisition of Barrett's esophagus surveillance biopsies |journal= Gastrointestinal Endoscopy|volume=70 |issue=6 |pages=1072–8.e1 |date=December 2009 |pmid=19595312 |doi=10.1016/j.gie.2009.04.009 }}</ref> It may cause chromatin to be squeezed out of nuclei.<ref name="Chatterjee2014">{{cite journal|last1=Chatterjee|first1=Shailja|title=Artefacts in histopathology|journal=Journal of Oral and Maxillofacial Pathology|volume=18|issue=4|year=2014|pages=S111–S116|issn=0973-029X|doi=10.4103/0973-029X.141346|pmid=25364159|pmc=4211218 |doi-access=free }}</ref> Inflammatory and tumor cells are most susceptible to crush artifacts.<ref name="Chatterjee2014"/>
<gallery mode="packed" heights="130"> File:Cellulose contamination in H&E and polarized light.jpg|Cellulose '''contamination''', in H&E stain and polarized light File:Histopathology of cardiac muscle with contamination from thyroid tissue.jpg|Cardiac muscle (bottom) with '''contamination''' from thyroid tissue (center) File:Crush artifact from forceps.jpg|'''Crush''' artifact from compression by forceps on the tissue sample File:Skin with folds and crush artifact by needle.jpg|'''Folding''' artifacts (white arrows) and a crush artifact (black arrow, with cytoplasmic hypereosinophilia and nuclear pleomorphism) from a needle File:Microscopy of liver parenchyma with tearing artifacts.jpg|'''Tearing''' artifacts, such as can be caused by:<br>- Microtomy with a nick or blemish in the knife edge.<ref name="TaqiSami2018">{{cite journal|last1=Taqi|first1=SyedAhmed|last2=Sami|first2=SyedAbdus|last3=Sami|first3=LateefBegum|last4=Zaki|first4=SyedAhmed|title=A review of artifacts in histopathology|journal=Journal of Oral and Maxillofacial Pathology|volume=22|issue=2|year=2018|pages=279|issn=0973-029X|doi=10.4103/jomfp.JOMFP_125_15|pmid=30158787|pmc=6097380 |doi-access=free }}</ref><br>- Traction of the sections.<br>- Too much or too little alcohol dehydration.<ref name="TaqiSami2018"/><br>- Sectioning calcified parts, which can be decalcified or removed.<ref name="TaqiSami2018"/> File:Formalin pigment artifacts.jpg|'''Formalin pigment''' artifacts File:Air bubble entrapment artifact.png|Air bubble entrapment artifact in a shoulder joint biopsy File:Staining artifacts by residual wax.jpg|'''Staining''' artifacts by residual wax, resulting in pale areas where cellular structures are not discernible File:Histopathology of radically excised basal-cell carcinoma with separation artifact (horizontal layout).jpg|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. File:Micrograph of stacked cells.jpg|'''Stacking''' of cells on top of each other gives a dark look, and in this breast tissue it may mimic microcalcifications. File:Pap smear of a monocyte with nuclear smearing artifact.jpg|Pap stained smear of a monocyte with nuclear smearing or smudging artifact, seen as a tail-like extension of nuclear material File:Histopathology of small cell carcinoma - nuclear smudging.png|Small cell carcinoma is a cancer where the presence of smudging is a clue to the diagnosis.<ref>Image by Mikael Häggström, MD. Source for findings: {{cite web|url=https://www.pathologyoutlines.com/topic/lungtumorsmallcell.html|title=Lung - Small cell carcinoma|website=Pathology Outlines|author=Caroline I.M. Underwood, M.D., Carolyn Glass, M.D., Ph.D.}} Last author update: 20 September 2022</ref> </gallery>
==In radiography== In projectional radiography, visual artifacts that can constitute disease mimics include jewelry, clothes and skin folds.<ref>[https://books.google.com/books?id=NItlwYj0aLcC&pg=PA46 Page 46] in: {{cite book|title=Pocket Tutor Chest X-Ray Interpretation|author=Michael Darby, Nicholas Maskell, Anthony Edey, Ladli Chandratreya|publisher=JP Medical Ltd|year=2012|isbn=9781907816062}}</ref> <gallery mode="packed"> File:Skin folds close to a hip fracture (with arrows).jpg|A hip fracture (black arrow) next to a skin fold (white arrow) File:Bed sheets artifact on lateral chest radiograph.jpg|Bed sheets looking like lung opacities on a chest radiograph </gallery>
==In magnetic resonance imaging== {{Main|MRI artifact|Ghosting (medical imaging)}} In Magnetic resonance imaging, artifacts can be classified as patient-related, signal processing-dependent or hardware (machine)-related.<ref name="ErasmusHurter2004">{{cite journal|last1=Erasmus|first1=L.J.|last2=Hurter|first2=D.|last3=Naude|first3=M.|last4=Kritzinger|first4=H.G.|last5=Acho|first5=S.|title=A short overview of MRI artifacts|journal=South African Journal of Radiology|volume=8|issue=2|pages=13|year=2004|issn=2078-6778|doi=10.4102/sajr.v8i2.127|doi-access=free}} [https://creativecommons.org/licenses/by/4.0/ (CC-BY 4.0)]</ref>
==References== {{Reflist}}
Category:Computer graphic artifacts Category:Visual artifacts