Editing Indigo (section)

===Modern spectral classification===
Several modern sources place indigo in the [[electromagnetic spectrum]] between 420 and 450 nanometers,<ref name="EoF" /><ref name="Huris">{{cite web|url=http://www.huris.com/web/cog/sci/phs/phy/emr.htm|title=Spectrum of Electromagnetic Radiation ( EMR )|first=The HURIS|last=Group|website=www.huris.com|access-date=14 June 2013|archive-date=28 January 2020|archive-url=https://web.archive.org/web/20200128045739/http://www.huris.com/web/cog/sci/phs/phy/emr.htm|url-status=dead}}</ref><ref name="VIBGYOR">{{cite web|url=http://www.mathworks.com/matlabcentral/fileexchange/20718-vibgyor-color-segmentation/content/VIBGYORsegmentation.m|title=VIBGYOR Color Segmentation – File Exchange – MATLAB Central|website=www.mathworks.com|date=June 2023|access-date=14 June 2013|archive-date=19 October 2013|archive-url=https://web.archive.org/web/20131019103723/http://www.mathworks.com/matlabcentral/fileexchange/20718-vibgyor-color-segmentation/content/VIBGYORsegmentation.m|url-status=live}}</ref> which lies on the short-wave side of [[Shades of blue#Blue (RGB) (X11 blue)|color wheel (RGB) blue]], towards (spectral) violet.

The correspondence of this definition with colors of actual indigo dyes, though, is disputed. Optical scientists Hardy and Perrin list indigo as between 445<ref>{{cite web |url=https://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html |title=What Wavelength Goes with a Color? |access-date=24 November 2016 |url-status=dead |archive-url=https://web.archive.org/web/20161124160412/https://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html |archive-date=24 November 2016 }}</ref> and 464&nbsp;nm wavelength,<ref>Arthur C. Hardy and Fred H. Perrin. ''[http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=22&SID=2EdCK2KejLbni4FJpgB&page=1&doc=1&colname=BIOSIS The Principles of Optics.]'' McGraw-Hill Book Co., Inc., New York. 1932.</ref> which occupies a spectrum segment from roughly the color wheel (RGB) blue extending to the long-wave side, towards [[azure (color)|azure]].

Other modern [[colorimetry|color scientists]], such as Bohren and Clothiaux (2006), and J.W.G. Hunt (1980), divide the spectrum between violet and blue at about 450&nbsp;nm, with no hue specifically named indigo.<ref name=Bohren>{{cite book | url = https://books.google.com/books?id=1oDOWr_yueIC&q=indigo+spectra+blue+violet+date:1990-2007&pg=PA214 | title = Fundamentals of Atmospheric Radiation | author = Craig F. Bohren and Eugene E. Clothiaux | publisher = Wiley-VCH | year = 2006 | isbn = 978-3-527-40503-9 }}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name=hunt>{{cite book | title = Measuring Color | author = J. W. G. Hunt | year = 1980 | publisher = Ellis Horwood Ltd | isbn = 978-0-7458-0125-4}}</ref>