Editing Infrared (section)

=== Art conservation and analysis ===

[[File:Infrared reflectograms of Mona Lisa.jpg|thumb|left|upright=0.8|An infrared reflectogram of ''[[Mona Lisa]]'' by [[Leonardo da Vinci]]]]
[[File:Infrared reflectography-en.svg|frameless|right|upright=0.9]]
Infrared reflectography<ref>{{Cite web |title=IR Reflectography for Non-destructive Analysis of Underdrawings in Art Objects |url=http://www.sensorsinc.com/artanalysis.html |url-status=dead |archive-url=https://web.archive.org/web/20081208052302/http://www.sensorsinc.com/artanalysis.html |archive-date=2008-12-08 |access-date=2009-02-20 |publisher=Sensors Unlimited, Inc.}}</ref> can be applied to paintings to reveal underlying layers in a non-destructive manner, in particular the artist's [[underdrawing]] or outline drawn as a guide.  Art conservators use the technique to examine how the visible layers of paint differ from the underdrawing or layers in between (such alterations are called [[pentimenti]] when made by the original artist). This is very useful information in deciding whether a painting is the [[prime version]] by the original artist or a copy, and whether it has been altered by over-enthusiastic restoration work. In general, the more pentimenti, the more likely a painting is to be the prime version. It also gives useful insights into working practices.<ref>{{Cite web |title=The Mass of Saint Gregory: Examining a Painting Using Infrared Reflectography |url=http://www.clevelandart.org/exhibcef/ConsExhib/html/grien.html |url-status=dead |archive-url=https://web.archive.org/web/20090113225836/http://www.clevelandart.org/exhibcef/ConsExhib/html/grien.html |archive-date=2009-01-13 |access-date=2009-02-20 |publisher=The Cleveland Museum of Art}}</ref> Reflectography often reveals the artist's use of [[carbon black]], which shows up well in reflectograms, as long as it has not also been used in the ground underlying the whole painting. Infrared reflectography can be realized by modified commercial digital cameras in the NIR spectral region or by dedicated instruments in the SWIR spectral region. <ref>{{Cite journal |last=Ambrosini |first=D. |last2=Daffara |first2=C |last3=Di Biase |first3=R. |last4=Paoletti |first4=D. |last5=Pezzati |first5=L. |last6=Bellucci |first6=R. |last7=Bettini |first7=F. |date=13 November 2009 |title=Integrated reflectography and thermography for wooden painting diagnostics |url=https://www.academia.edu/download/92580972/Integrated_reflectography_and_thermography_for_wood_2010_Journal_of_Cultural.pdf |journal=Journal of Cultural Heritage |volume=11 |pages=196-204}}</ref> The recent extension of reflectography into the MWIR spectral region<ref>{{Cite journal |last=Daffara |first=C. |last2=Ambrosini |first2=D. |last3=Pezzati |first3=L. |last4=Paoletti |first4=D. |date=18 June 2012 |title=Thermal-quasi-reflectography: a new imaging tool in art conservation |url=https://opg.optica.org/oe/fulltext.cfm?uri=oe-20-13-14746 |journal=Optics Express |volume=20 |issue=13 |pages=14746-14753}}</ref><ref>{{Cite journal |last=Daffara |first=C. |last2=Parisotto |first2=S. |last3=Mariotti |first3=P. I. |last4=Ambrosini |first4=D. |date=18 November 2021 |title=Dual mode imaging in mid infrared with thermal signal reconstruction for innovative diagnostics of the “Monocromo” by Leonardo da Vinci |url=https://www.nature.com/articles/s41598-021-01837-8 |journal=Scientific Reports |volume=11 |pages=22482}}</ref> has proved capable of detecting subtle differences in surface materials. 

Finally, NIR reflectography can be performed with good results using smartphone cameras .<ref>{{Cite journal |last=Daffara |first=C. |last2=Ambrosini |first2=D. |date=14 August 2024 |title=Smartphone-based diagnostics with coherent and infrared imaging for cultural heritage |url=https://iopscience.iop.org/article/10.1088/2515-7647/ad6abc |journal=Journal of Physics: Photonics |volume=6 |pages=045006}}</ref>
<!--this is somewhat pointless without an accompanying I.R.:  Among many other changes in the [[Arnolfini Portrait]] of 1434 (left), the man's face was originally higher by about the height of his eye; the woman's was higher, and her eyes looked more to the front. Each of his feet was underdrawn in one position, painted in another, and then overpainted in a third. These alterations are seen in infrared reflectograms.<ref>National Gallery Catalogues: The Fifteenth Century Netherlandish Paintings by Lorne Campbell, 1998, {{ISBN|1-85709-171-X}}, {{OL|392219M}}, {{OCLC|40732051}}, {{LCCN|98066510}}, (also titled ''The Fifteenth Century Netherlandish Schools''){{Page needed|date=September 2010}}.</ref>-->

Recent progress in the design of infrared-sensitive cameras makes it possible to discover and depict not only underpaintings and pentimenti, but entire paintings that were later overpainted by the artist.<ref>[http://colourlex.com/project/ir-reflectography/ Infrared reflectography in analysis of paintings] {{Webarchive|url=https://web.archive.org/web/20151222133807/http://colourlex.com/project/ir-reflectography/ |date=2015-12-22 }} at ColourLex.</ref> Notable examples are [[Picasso]]'s ''[[Woman Ironing]]'' and ''[[Blue Room (Picasso)|Blue Room]]'', where in both cases a portrait of a man has been made visible under the painting as it is known today.

Similar uses of infrared are made by conservators and scientists on various types of objects, especially very old written documents such as the [[Dead Sea Scrolls]], the Roman works in the [[Villa of the Papyri]], and the Silk Road texts found in the [[Dunhuang Caves]].<ref>{{Cite web |title=International Dunhuang Project An Introduction to digital infrared photography and its application within IDP |url=http://idp.bl.uk/pages/technical_resources.a4d |url-status=dead |archive-url=https://web.archive.org/web/20081202000830/http://idp.bl.uk/pages/technical_resources.a4d |archive-date=2008-12-02 |access-date=2011-11-08 |publisher=Idp.bl.uk}}</ref> Carbon black used in ink can show up extremely well.