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Color and Appearance Standardization

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Color and Appearance Standardization Color and Appearance Standardization December 6, 2016 Schoolcraft College – VisTaTech Center Livonia, MI Nick Lena Director of Color Technology GTI Graphic Technology, Inc. Revisions in Recommended Practice SAE J 361 2016 “Procedure for Visual Evaluation of Interior and Exterior Automotive Trim” 1. SCOPE This practice requires judgments by observers with a minimum of normal color vision and preferably superior as rated with the FM-100Hue Test as specified in ASTM E1499, Guide for Selection, Evaluation, and Training of Observers. Superior Color Discrimination About 16% of the population make 0 to 4 transpositions on the first test, or total error scores of 0 to 16. Average / Normal Color Discrimination About 68% of the population score between 20 and 100 on first tests. This is a normal range of competence for color discrimination. 2.1.2 CIE Publication Available from CIE www.cie.co.at ISO/CIE Publication ISO 23603/CIE S012 Standard Method for Assessing the Spectral Quality of Daylight for Visual Appraisal and Measurement of Color Previously designated as CIE Publication 51.2. 4.1.1 Daylight capable of providing a color temperature of 6500 K ± 200 K at an illuminance of 1080 to 1730 lux (100 to 160 ft-candles). Although typically provided by filtered Tungsten Halogen Lamps, Daylight Fluorescent lamps with equivalent spectral and illuminance characteristics can be used as an acceptable alternative. The resulting spectral power distribution of the incident light must be maintained to conform to ASTM E 308 and ISO/CIE Publication ISO 23603 / CIE S 012 with a grade of B/C or better. Correlated Color Temperature, CCT and Color Rendering, CRI are both very weak specifications for daylight sources. ASTM D1729 2016, AATCC Procedure 9, SAE J-361, ISO 3664 and BS- 950 all specify a quality grade of B/C or better based on ISO/CIE Standard ISO 23603:2005(E) / CIE S 012/E:2004 “Standard method of assessing the spectral quality of daylight simulators for visual appraisal and measurement of colour” (Previously CIE Publication 51) • Tests Spectral Quality of Daylight Simulators for Visual Appraisals and Instrumental Measurements. • Includes Test Methods for D50, D55, D65, and D75. • Uses 5 Virtual Metamer Sets for Visible and 3 for Ultraviolet. • Quality Grades are Based on Delta E or total color difference of the Metamer Sets. • More Accurate than CCT or CRI for Evaluating the quality of a Daylight Simulation. There are Various Qualities of Daylight Simulations •Fluorescent Daylight Three (3) Phosphor Narrow Band, Tri-Band Three (3) Phosphor Wide Band Five (5) Phosphor Wide Band Seven (7) Phosphor Wide Band Nine (9) Phosphor Wide Band •Filtered Tungsten Halogen 1.6 1.4 Tungsten lamp 1.2 1.2 D65 simulator Illuminant D65 1 RGB 2 •Pulsed or Continuous Xenon 1.0 White 2 0.8 0.8 D65 0.6 0.6 •Light Emitting Diodes values) SPD(relative 0.4 0.4 0.2 SPDunits) (relative 0.2 0.0 300 350 400 450 500 550 600 650 700 750 800 Wavelength (nm) 0 350 400 450 500 550 600 650 700 750 800 Wavelength (nm) CIE 192:2010 Practical Daylight Sources for Colorimetry TC1-44 ISO/CIE Standard ISO 23603:2005(E) / CIE S 012/E:2004 Quality Grade Metamerism Index CIELAB CIELUV A < 0.25 < 0.32 B 0.25 to 0.50 0.32 to 0.65 C 0.50 to 1.00 0.65 to 1.30 D 1.00 to 2.00 1.30 to 2.60 E > 2.00 > 2.60 Product Color CRI MI Rating Temp. Daylight 6519K 96 0.23 A Filtered 6472K 95 0.26 A or B Daylight Fluorescent 6544K 97 0.28 B Daylight Commercial 6493K 96 1.52 D Daylight 4.1.2 Cool White Fluorescent (CWF) capable of providing a color temperature of 4150 K ± 200 K at a minimum illuminance of 860 lux (80 ft- candles). This source is typically provided by Cool White Fluorescent tubes simulating Standard Illuminant F2. Note: Changes in energy legislation has altered the spectral power of some Cool White lamps to more closely simulate Standard Illuminant F11. Illuminant F2 CWF CWF Deluxe 4.4 Color Temperature Measuring Instrument A spectroradiometer or colorimeter must be used to check color temperature of the light sources. These units must be calibrated using a NIST traceable 6500 K source. Only a Spectroradiometer with current traceability and capable of measuring 300 to 700 nm in a minimum of 5 nm intervals can be used for calibration and re-certification as specified in ISO 23603 / CIE S 012. Other Standards Activities • ASTM E12.11 Visual Methods D1729-2016 Standard Practice for Visual Appraisal of Colors and Color Differences of Diffusely- Illuminated Opaque Materials (January 2016) • Work of AATCC and CIE on 5 to 8 new standard illuminants LED’s in early 2017 • AATCC new role in developing weighting functions for new illuminants (ASTM E308) • AATCC to endorse use of CIE DE2000 for Textile (CMC) • AATCC to continue work on illuminance levels required for color matching • LED Technical Conference, May 2017 AATCC Lighting changes, developments, and trends (LED’s and Daylight LED’s) LED Color or OLEDs Only a limited set of semiconductor materials, substrates, and doped phosphors can be used to create color LEDs. Semiconductor materials like Aluminum Gallium Arsenide (AlGaAs) Aluminum Gallium Indium Phosphide (AlGaInP), Gallium III Phosphide (GaP), Indium Gallium Nitride (InGaN), and Zinc Selenide (ZnSe) are used to provide energy at specific wavelengths or colors. Blue LED colors remain the most difficult color to produce. Lighting changes, developments, and trends (LED’s) LED sources are an available option in most new viewing booths. Linear LED lamps which operate off electronic T8 fluorescent ballasts may be added to existing viewing booths. Older viewing booths with T12 Lamps cannot be easily converted or retrofitted. GE LED ( 36" lamps (2) in CMB-2540 - 24 hour burn-in 2.00000E-05 1.80000E-05 1.60000E-05 1.40000E-05 0.0007 Philips 24 inch InstantFit LED lamps - 1.20000E-05 0.0006 Non-Dimmable 1.00000E-05 0.0005 8.00000E-06 3000K 6.00000E-06 0.0004 3500K 4.00000E-06 0.0003 4000K 2.00000E-06 0.0002 0.00000E+00 300.00 400.00 500.00 600.00 700.00 800.00 0.0001 0.0000 350 400 450 500 550 600 650 700 Lighting changes, developments, and trends (LED’s and Daylight LED’s) White LED Color LED’s A white LED has the appearance of white light but is really a blue LED with an orange phosphor added. White LEDs fade rapidly over time. Available colors are limited because of expense. LED color is a function of semiconductor material and phosphors used in the manufacturing process. The real driver for LEDs is to achieve higher light output and lower energy costs color must be sacrificed so not to forfeit efficiency. Lighting changes, developments, and trends (LED’s and Daylight LED’s) Even though blending LEDs may have promise, constant monitoring, tweaking, and calibration to maintain any kind of color accuracy is required at great expense to the end user. Lighting changes, developments, and trends (LED’s and Daylight LED’s) The lighting industry has experienced an increase in poorly designed and manufactured LED products. LEDs can flicker, they can dim after warm up, they will shift in color over time, can draw power even when they are turned “off”, or they can have uniformity issues in less than a year of regular use. Until stability, heat output, color stability, and life issues are corrected and controlled, LED technology becomes another of those new lighting technologies, like compact fluorescent, which comes to us with a lot of promise in energy savings, extended life, and exceptional color capabilities but ultimately falls short in the promises. Lighting changes, developments, and trends DOE and IES TM-30-15 Metric for evaluation and review to Replace CRI TM-30-15 uses 99 colors not 8 as used in CRI Calculates a Color Fidelity Index (Rf) 0 to 100 quantifies the accurate rendition of colors, or how similar they will be in comparison to a reference illuminant. Calculates a Color Gamut Index (Rg) 60-140 when Rf > 60 Color Vector Graphic and Hue Bin Chroma Shift F32T8/735 F32T8/835 Blue-Pump Phosphor LED (81 CRI) Ra 74, LER 348 Ra 85, LER 343 Ra 83, LER 309 Lighting changes, developments, and trends DOE and IES TM-30-15 Metric for evaluation and review to Replace CRI IES TM‐30‐15 • CIE CRI metric can be optimized by lighting design due to use of 8 pastel Munsell colors and 7 supplementary colors • TM‐30‐15 samples entire spectrum, entire colorspace – 99 colors • Not subject to “optimization” that does not reflect actual color quality. • TM‐30‐15 rewards sources with preferred color fidelity Webinars describing TM‐30‐15 http://energy.gov/eere/ssl/webinar‐understanding‐and‐applying‐TM‐30‐15 IES Method for Evaluating Light Source Color Rendition www.ies.org Lighting Recommendations • Know what light source or combination of sources are really being used. • Be familiar with the requirements of National and International Standards and/or Corporate Lighting Specifications like ISO 3664, ASTM- 1729, SAEJ- 361, BS-950 and AATCC Procedure 9 and any company specified standards that you should conform to. • Understand the differences and capabilities of Colorimeter / Tristimulus Instruments and spectrally based instruments like Spectroradiometers. They can provide very different lighting measurements. • Be aware of the common lighting metrics and deficiencies they may cause when specifying lighting based on Chromaticity Coordinates, Correlated Color Temperature, or Color Rendering. • Request the Spectral Power Distribution curves and CIE assessment calculations for your lighting.
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