NEMA LSCR-PP 1-2015 Light Source Color Rendition.pdf

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1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA LSCR-PP 1-2015Light Source Color RenditionA NEMA Lighting Systems Division Position Paper on IES TM-30-15 LSCR-PP 1-2015 Light Source Color Rendition Prepared by NEMA Luminaire Section National Electrical Manufacturers Assoc

2、iation 1300 North 17thStreet, Suite 900 Rosslyn, Virginia 22209 Approved: November 12, 2015 www.nema.org NEMA LSCR-PP 1-2015 2015 National Electrical Manufacturers Association NEMA supports the concept of providing information on the color gamut/saturation of LED light sources after international ag

3、reement on a calculation method has been reached. At this time, NEMA opposes any mandatory reporting or performance requirements for IES-Rfor IES-Rg. Characterizing color quality is difficult because there are many aspects to be considered. A full evaluation of color quality should include applicati

4、on, color saturation, chromaticity preference, and white light perception in addition to a color fidelity metric, such as the International Commission on Illuminations (CIE) general color rendering index (Ra).1Any single-number fidelity measure (such as Ra orthe new Rf) that averages the results of

5、many colors in a light source could possibly have a high numerical value and yet perform poorly with some specific colors. The Illuminating Engineering Society (IES) has recently published TM-30-15, “IES Method for Evaluating Light Source Color Rendition.”2Similar to other recent proposals (see3for

6、instance), it addresses the limitations of CIEs Raby defining two measures: a fidelity index, IES-Rf, and a gamut area index, IES-Rg. TM-30-15 also defines a “gamut area polygon” created from the average chromaticity coordinates of 99 color evaluation samples within 16 color regions. The reference i

7、lluminant is nearly identical to an incandescent lamp operating at the same temperature. The IES-Rgmetric can have a value greater than 100 and yet saturation might be lower than the reference light source for certain colors. The IES fidelity and gamut area indices are interrelated. If the fidelity

8、index Rfis 100, then the tested light source is equal to the reference illuminant for all color evaluation samples, and the resulting color saturation Rgis fixed at 100. In this case, there is no freedom to adjust the amount of saturation to enhance user preference. Saturation can be increased above

9、 100 only when the test source is different from the reference illuminant, which inevitably reduces the fidelity index. A fidelity index alone cannot assess the preference for color rendering of objects in a specific environment. In side-by-side tests of light sources having equal chromaticity and R

10、a, in many cases, observers find light sources with lower fidelity index, Rf, to be more natural.4For example, in some applications, people tend to prefer light sources with extra red. There are trade-offs between fidelity and gamut area indices based on any reference illuminant and human color pref

11、erence. IES TM-30-15 is a Technical Memorandum and is an initial step toward new metrics to describe light source color. It is not a required standard, nor does it provide design guidance or criteria for best practices.5It presents an invitation to the lighting community to evaluate the proposed IES

12、 methods. The IES, in its position statement on color rendering index, “does not endorse mandatory color rendering measures in energy regulations until there is a national or international consensus regarding an appropriate metric and range of values.” The IES method has been proposed to CIE for int

13、ernational adoption. The CIE technical committees must carefully study the IES proposal, which might result in some adjustments of the calculation procedure, color space, color evaluation samples, and reference illuminant. It is premature to consider IES TM-30-15 as a mandatory requirement or regula

14、tion because the metrics are likely to evolve. Color Rendering Index (CRI) has been with us for 50 years. Whatever the lighting community adopts as its replacement likely will be in use for decades, as well. The industry has an opportunity to develop a significantly improved alternative to CRI. Adop

15、tion of a new metric without a thorough vetting process will result in unintended and negative consequences. 1Commission Internationale de lEclairage, Method of Measuring and Specifying Colour Rendering Properties of Light Sources. CIE Publication 13.3, Vienna: CIE 13.3, 1995 2IES TM-30-15. IES Meth

16、od for Evaluating Light Source Color Rendition. https:/www.ies.org/store/product/ies-method-for-evaluating-light-source-color-rendition-3368.cfm 3Freyssinier J, Rea M. A two-metric proposal to specify the color-rendering properties of light sources for retail lighting. In: Proceedings of SPIE 2010,

17、Tenth International Conference on Solid State Lighting; 7784: 77 840V-1. San Diego, California, USA, August 2-4: 2010 4Ohno Y, Fein M, Miller C. Vision experiment on chroma saturation for color quality preference. In: Proceedings of the 28th CIE session 2015; CIE 216:2015, Volume 1, Part 1; pp. 60-6

18、9. Manchester, United Kingdom, June 28July 4: 2015 5IES Position Statement on Color Rendering Index, PS-8-15, www.ies.org/PDF/PositionStatements/PS-8-15.pdf NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB