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June 24, 2016
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  • IES Method for Evaluating Light Source Color Rendition
    IES Method for Evaluating Light Source Color Rendition
    Click To Enlarge
    2015 – 26 pages
    8 ½ X 11 Softcover
    ISBN # 978-0-87995-312-6
    List Price: $50.00
    IES Member Price: $35.00 
    Order # TM-30-15

    Product ID: TM-30-15
    Price: $50.00
    Member Price: $35.00
    Product Detailed Description

    Accurately quantifying the color rendition characteristics of a light source is a complex problem. Many aspects of color rendition, such as color fidelity, color discrimination, or color preference, should be simultaneously considered during the design and specification process. There is no one metric or measure that can accurately quantify all aspects of color rendition and/or identify the most desirable light source for every application.

    This Technical Memorandum describes a method for evaluating light source color rendition that takes an objective and statistical approach, quantifying the fidelity (closeness to a reference) and gamut (increase or decrease in chroma) of a light source. The method also generates a color vector graphic that indicates average hue and chroma shifts, and which helps with interpreting the values of
    Rf and Rg. 

    TM-30-15 provides equations and direction for calculating Rf and Rg, including the spectral reflectance functions for the 99 CES. It is accompanied by a software tool to aid in calculation and display of the results (access information for the software tool is provided in the publication). The IES TM-30-15 color rendition method consolidates and synthesizes numerous research efforts that have been ongoing for several years, and was developed by representatives of the manufacturing, specification, and research segments of the lighting industry. 

    Definitions, Variables, and Procedure

    Colorimetric Observer

    Test Source

    Reference Illuminan

    Color Evaluation Samples (CES)

    Range and Interpolation of Data

    Calculation of Tristimulus Values

    Color Space and Chromatic Adaptation Transformation

    Calculation of Chromaticity Coordinates

    Color Difference Formula

    Fidelity Index (Rf)

    Gamut Index (Rg)

    Two-axis System

    Fidelity measures for specific hues angle bins and color samples

    Flow Chart

    Limitations and Notes

    Average Values

    Comparison Across CCTs

    Energy Efficiency

    Color Samples

    Preferred Chromaticity

    Fluorescence and Whiteness

    Color Rendition Preference

    Annex A - Spectral Reflectance Factors
    Annex B - Color Evaluation Samples

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