Editing Mach bands (section)

==In radiology==
[[File:Mach_band_cross.svg|thumb|An illusory cross (×) appears in the large image due to gradient discontinuity<ref>{{Cite report |chapter-url=https://ieeexplore.ieee.org/document/8946114 |chapter=Radiography Contrast Enhancement: Smoothed LHE Filter a Practical Solution for Digital X-Rays with Mach Band |last1=Ambalathankandy |first1=Prasoon |last2=Ou |first2=Yafei |date=December 2019 |publisher=IEEE |doi=10.1109/DICTA47822.2019.8946114 |pages=1–8 |last3=Kochiyil |first3=Jyotsna |last4=Takamaeda |first4=Shinya |last5=Motomura |first5=Masato |last6=Asai |first6=Tetsuya |last7=Ikebe |first7=Masayuki|title=2019 Digital Image Computing: Techniques and Applications (DICTA) |isbn=978-1-7281-3857-2 }}</ref>]]
This visual phenomenon is important to keep in mind when evaluating [[dental radiography|dental radiographs]] for evidence of decay, in which [[grayscale]] images of teeth and bone are analyzed for abnormal variances of density. A [[false-positive]] radiological diagnosis of [[dental caries]] can easily arise if the practitioner does not take into account the likelihood of this illusion. Mach bands manifest adjacent to metal restorations or appliances{{Citation needed|date=June 2013}} and the boundary between [[Tooth enamel|enamel]] and [[dentin]].<ref>{{Cite book |last=Devlin |first=Hugh |title=Operative dentistry: a practical guide to recent innovations; with ... 5 tables |date=2006 |publisher=Springer |isbn=978-3-540-29616-4 |location=Berlin Heidelberg |pages=11}}</ref> Mach bands may also result in the misdiagnosis of horizontal root fractures because of the differing radiographic intensities of tooth and bone.<ref>{{Cite journal |last=Nielsen |first=C |date=November 2001 |title=Effect of Scenario and Experience on Interpretation of Mach Bands |url=http://linkinghub.elsevier.com/retrieve/pii/S0099239905604852 |journal=Journal of Endodontics |language=en |volume=27 |issue=11 |pages=687–691 |doi=10.1097/00004770-200111000-00009|pmid=11716082 |url-access=subscription }}</ref>

Mach effect can also lead to an erroneous diagnosis of [[pneumothorax]] by creating a dark line at the lung periphery (whereas a true pneumothorax will have a white pleural line).<ref>{{Cite journal | last1 = Parker | first1 = M. S. | last2 = Chasen | first2 = M. H. | last3 = Paul | first3 = N. | doi = 10.2214/AJR.07.7081 | title = Radiologic Signs in Thoracic Imaging: Case-Based Review and Self-Assessment Module | journal = American Journal of Roentgenology | volume = 192 | issue = 3_Supplement | pages = S34-48 | year = 2009 | pmid =  19234288| s2cid = 34785665 }}</ref>