Editing Color temperature (section)

==Spectral power distribution==
[[File:Spectral Power Distributions.png|right|frame|Characteristic spectral power distributions (SPDs) for an [[Incandescent light bulb|incandescent lamp]] (left) and a [[fluorescent lamp]] (right). The horizontal axes are wavelengths in [[nanometer]]s, and the vertical axes show relative intensity in arbitrary units.]]

Light sources and illuminants may be characterized by their [[spectral power distribution]] (SPD). The relative SPD curves provided by many manufacturers may have been produced using 10&nbsp;[[nanometer|nm]] increments or more on their [[spectroradiometer]].<ref>Gretag's [http://www.xrite.com/documents/literature/gmb/en/200_spectrolino_manual_en.pdf SpectroLino] {{webarchive|url=https://web.archive.org/web/20061110131804/http://www.xrite.com/documents/literature/gmb/en/200_spectrolino_manual_en.pdf |date=2006-11-10 }} and X-Rite's [http://camerawholesalers.com/x-rites-color-munki-photo-competitive-comparison ColorMunki]  {{webarchive|url=https://web.archive.org/web/20090205040118/http://www.pictureline.com/images/pdf/L11-246%20CM%20CompetitCompr_03-17-08.pdf |archive-url=https://web.archive.org/web/20090205040118/http://www.pictureline.com/images/pdf/L11-246%20CM%20CompetitCompr_03-17-08.pdf |archive-date=2009-02-05 |url-status=live |date=2009-02-05 }} have an optical resolution of 10 nm.</ref> The result is what would seem to be a smoother ("[[full-spectrum light|fuller spectrum]]") power distribution than the lamp actually has. Owing to their spiky distribution, much finer increments are advisable for taking measurements of fluorescent lights, and this requires more expensive equipment.