Editing Color rendering index (section)

=== Alternatives ===
{{Main|Color rendering#Scales}}
{{Update|section|inaccurate=yes|date=November 2021}}
{{Harvtxt|CIE|2007}} "reviews the applicability of the CIE color rendering index to white LED light sources based on the results of visual experiments". Chaired by Davis, CIE TC 1-69(C) is currently investigating "new methods for assessing the color rendition properties of white-light sources used for illumination, including solid-state light sources, with the goal of recommending new assessment procedures [...] by March, 2010".<ref>[http://www.cie.co.at/div1/ActReps/D1ActivityReport08.pdf CIE Activity Report. Division 1: Vision and Color]. {{Webarchive|url=https://web.archive.org/web/20110706091259/http://www.cie.co.at/div1/ActReps/D1ActivityReport08.pdf|date=July 6, 2011}}, p. 21, January 2008.</ref>

For a comprehensive review of alternative color rendering indexes see {{harvtxt|Guo|Houser|2004}}.

{{harvtxt|Smet|2011}} reviewed several alternative quality metrics and compared their performance based on visual data obtained in nine psychophysical experiments. It was found that a geometric mean of the GAI index and the CIE Ra correlated best with naturalness (r=0.85), while a color quality metric based on memory colors (MCRI<ref>Smet K. A. G., Ryckaert W. R., Pointer M. R., Deconinck G., Hanselaer P. Colour Appearance Rating of Familiar Real Objects. Colour Research and Application 2011; 36(3):192–200.</ref>) correlated best for preference (''r''&nbsp;= 0.88). The differences in performance of these metrics with the other tested metrics (CIE Ra; CRI-CAM02UCS; CQS; RCRI; GAI; geomean (GAI, CIE Ra); CSA; Judd Flattery; Thornton CPI; MCRI) were found to be statistically significant with ''p''&nbsp;< 0.0001.<ref>Smet K. A. G., Ryckaert W. R., Pointer M. R., Deconinck G., Hanselaer P. [http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww.opticsinfobase.org%2FDirectPDFAccess%2F3AAAA211-C63E-79CC-4E0A0772E17419BA_212731.pdf%3Fda%3D1%26id%3D212731%26seq%3D0%26mobile%3Dno&org= Correlation between color quality metric predictions and visual appreciation of light sources].</ref>

Dangol, et al., performed psychophysical experiments and concluded that people's judgments of naturalness and overall preference could not be predicted with a single measure, but required the joint use of a fidelity-based measure (e.g., Qp) and a gamut-based measure (e.g., Qg or GAI.).<ref>{{cite journal |last1=Dangol |first1=R |last2=Islam |first2=M |last3=LiSc |first3=M Hyvärinen |last4=Bhusal |first4=P |last5=Puolakka |first5=M |last6=Halonen |first6=L |title=Subjective preferences and colour quality metrics of LED light sources |journal=Lighting Research & Technology |date=December 2013 |volume=45 |issue=6 |pages=666–688 |doi=10.1177/1477153512471520 }}</ref> They carried out further experiments in real offices evaluating various spectra generated for combination existing and proposed color rendering metrics.<ref>{{cite journal|last1=Dangol|first1=R|last2=Islam|first2=MS|last3=Hyvärinen|first3=M|last4=Bhushal|first4=P|last5=Puolakka|first5=M|last6=Halonen|first6=L|year=2015|title=User acceptance studies for LED office lighting: Preference, naturalness and colourfulness|journal=Lighting Research & Technology|volume=47|pages=36–53|doi=10.1177/1477153513514424 }}</ref><ref>{{cite journal|last1=Islam|first1=MS|last2=Dangol|first2=R|last3=Hyvärinen|first3=M|last4=Bhusal|first4=P|last5=Puolakka|first5=M|last6=Halonen|first6=L|year=2013|title=User acceptance studies for LED office lighting: Lamp spectrum, spatial brightness and illuminance|journal=Lighting Research & Technology|volume=47|pages=54–79|doi=10.1177/1477153513514425 }}</ref><ref>{{cite journal|last1=Baniya|first1=R. R.|last2=Dangol|first2=R.|last3=Bhusal|first3=P.|last4=Wilm|first4=A.|last5=Baur|first5=E.|last6=Puolakka|first6=M.|last7=Halonen|first7=L.|date=2015|title=User-acceptance studies for simplified light-emitting diode spectra|journal=Lighting Research and Technology|volume=47|issue=2|pages=177–191|doi=10.1177/1477153513515264 }}</ref>

Due to the criticisms of CRI many researchers have developed alternative metrics, though relatively few of them have had wide adoption.

==== Gamut area index (GAI) ====
Developed in 2010 by Rea and Freyssinier, the gamut area index (GAI) is an attempt to improve over the flaws found in the CRI.<ref>{{cite journal | last1 = Rea | first1 = M. S. | last2 = Freysinnier-Nova | first2 = J. P. | year = 2008| title = Color rendering: A tale of two metrics | journal = Color Research and Application | volume = 33 | issue = 3| pages = 192–202 | doi = 10.1002/col.20399 }}</ref> They have shown that the GAI is better than the CRI at predicting color discrimination on standardized Farnsworth-Munsell 100 Hue Tests and that GAI is predictive of color saturation.<ref name="Color rendering: Beyond pride and prejudice - Rea - 2010 - Color Research & Application - Wiley Online Library" /> Proponents of using GAI claim that, when used in conjunction with CRI, this method of evaluating color rendering is preferred by test subjects over light sources that have high values of only one measure. Researchers recommend a lower and an upper limit to GAI. Use of LED technology has called for a new way to evaluate color rendering because of the unique spectrum of light created by these technologies. Preliminary tests have shown that the combination of GAI and CRI used together is a preferred method for evaluating color rendering.<ref>{{cite magazine |title=Light Levels |publisher=Alliance for Solid-State Illumination Systems and Technologies |magazine=Guide to Light and Color in Retail Merchandising |volume=8 |issue=1 |page=12 |date=March 2010 |url= http://www.lrc.rpi.edu/programs/solidstate/assist/pdf/AR-ColorGuideforRetailLighting-March2010.pdf |access-date=September 14, 2020 }}</ref><ref>{{cite magazine |title=Color Rendering |publisher=Alliance for Solid-State Illumination Systems and Technologies |magazine=Recommendations for Specifying Color Properties of Light Sources for Retail Merchandising |volume=8 |issue=2 |date=March 2010 |page=6 |access-date=September 14, 2020 |url= http://www.lrc.rpi.edu/programs/solidstate/assist/pdf/AR-SpecifyColorRec-March2010.pdf }}</ref>

==== Color quality scale (CQS) ====
{{Further|Color quality scale}}
{{harvtxt|Pousset|Obein|Razet|2010}} developed a psychophysical experiment in order to evaluate light quality of LED lightings. It is based on colored samples used in the "color quality scale". Predictions of the CQS and results from visual measurements were compared.