LED Lighting for Critical Color Judgement Lessons from 8 Years in the Field James S. Summers VP, Just Normlicht, Inc. www.justnormlicht.com
Background Selfie 30 years in color perception, reprographic technologies and color management across a range of industries, media and imaging processes Approach color as an amalgamation of business, technical and human factors to achieve success Vice President, Just Normlicht, Inc. and GL Optic
Just Normlicht Worldwide manufacturer of standardized lighting for controlled viewing and color matching environments Broad line of standard and custom products
GL Optic Light Measurement Solutions (a JUST subsidiary) Instruments and systems for quantified light measurements Product range from basic spectrometers to rack-mount laboratory equipment Accessories extend applications, designed for accuracy, durability and ease of use Software extends functionality, and integrates with a wide range of environments
Applications and Industries
Representative Customers
JUST LED Timeline Development multi-spectral LED technology LED Hybrid Luminaire LED Viewing Light LED Luminaire LED Calibration Source LED modulight & proofstation LED Production Lighting 2008 2010 2012 2014 2016
What is the objective? Source Object Observer
What is the objective? Source Object Observer Producing, hopefully, the expected result
Let s Start with You
Who s here Supply chain partners Scientists Designers, colorists, stylists Retailers and merchandisers Brand owners, managers, developers Product managers and specialists Buyers Color control providers Lighting suppliers Instrument manufacturers Educators, students
All with a common goal
The Observer
The Observer This is your eye if you are the standard observer
The standard observer From a thesis on the accuracy of the standard observer This raises the question if the current standard colorimetric observer has room for improvement. In other words, observers may have skewed the results of the mean. Another important factor to keep in mind is that the standard colorimetric observer was purely a mathematical construct.
The Object
Observing the Object Perception strongly influenced by: light intensity and uniformity viewing geometry fixture positioning gloss and glare ambient lighting surroundings etc and, of course, spectral distribution
The Light
Sources (aka lights )
Relative Power Described as Standard Illuminants 100% 90% 80% CIE D65 Illuminant (smoothed) CIE D65 Illuminant (5nm) 70% 60% 50% 40% 30% 20% 10% 0% 300 350 400 450 500 550 600 650 700 750 800 Wavelength (nm)
And not so standard Lights D65 vs
When in doubt, approximate Ideal Black Body Radiator
CCT is not enough... Correlated color temperature (CCT e.g. 5000 Kelvin) Only a general indicator Two different lamps with the same CCT may produce quite different visual results Color rendering index (CRI) helps How well certain colors match under the lamp vs. the standard illuminant Scale up to 100 and neither is CRI
LED Sources For color critical evaluations
LEDs Status for Color Critical Matching Standard LEDs insufficient Don t meet viewing standards CRI and Metamerism indicies poor Mis-match of peaks vs. other sources
LEDs Issues for Color Critical Matching Color matching LED challenges Large varianaces in chip peak wavelength Thermal change = color change Large production tolerances Manual selection (binning) Comparatively small demand Availability, Servicability
LEDs also the Solution Multi-spectral, multi-led approach Tightly controlled chip manufacturing Each LED chip individually controlled Active thermal management Multi-level calibration process from manufacturing to end-user Field and self-recalibration processes
JUST Multi-spectral LED light source Patented approach Even Spectral Power Distribution (ex. D50) CRI > 95 MI(vis) < 1.0 MI(uv) < 1.5 140 120 100 80 60 40 20 0 730nm 720nm 710nm 700nm 690nm 680nm 670nm 660nm 650nm 640nm 630nm 620nm 610nm 600nm 590nm 580nm 570nm 560nm 550nm 540nm 530nm 520nm 510nm 500nm 490nm 480nm 470nm 460nm 450nm 440nm 430nm 420nm 410nm 400nm 390nm 380nm D50 D50sim d50-uv
LEDs Color Critical Solutions Hybrid - LED Color Viewing LightHybrid with LED and fluorescent lamps
Software Controls adjust LEDcontrol SOFTWARE Unlimited number light simulations Selection of ambient light? Dimming & light source combintions Report function
Lessons from the Field LEDs Viewing Sources for Color Critical Applications
1. Learn every day LEDs are different that traditional sources Much of our experience, preconceived notions and predispositions of lighting must be reconsidered 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 30 35 40
2. LEDs are very different light sources With compelling benefits: Highly efficiency (>2x fluorescent) Low heat (comparatively) Long service life (potentially) Very stable over time No mercury 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 30 35 40 And important considerations: Light bandwidth narrow Luminous intensity distribution Flicker Angular color uniformity Optics are critical Production variability Rapid industry change
3. Color critcial viewing using LEDs is here Excellent simulation of standard illuminants and mixed sources D50, D65, D75, A Color spaces > srgb UV reveals impact of brighteners and fluorescent colorants Highly stable with proper design and calibration >10x longer lifetime compared with fluorescent lamps Environmentally friendly
4. Instruments are not a panacea Some elaboration Instruments are tools, some are better, some are worse, some are repeatable, but not accurate, some are accurate, but not repeatable some are linear, some are noisy Usefulness is as dependent on the operator and the interpretation of the results as much as it is upon the instrument itself
5. Assumptions State of Confusion? Better stated and related, than silent and assumed When discussing light, it s hard to be too specific D50 or 5000K? CRI and TM-30-15 Ra, R14 MIvis, MIuv Ambient light Which observer - 2 Standard, or 10 supplementary and color matching function (1931 vs. 1964); and color space (many)
6. Inspect what you expect Specifications and instruments are no substitute for keen observation, critical thinking, sound judgement and experience Overspecing increases initial costs and on-going overhead (inspection, maintenance, repair) Underspecing leads to misaligned expectations
7. LED light quantity does not trump quality More light of poor quality, is not better than less light of better quality Some sacrifice in efficiency is required for improved quality Improved Full-spectrum Light Quality Lowered Efficiency
8. LEDs can simulate multiple illuminants, but other sources cannot simulate LEDs you can teach a new dog old tricks, but you can t teach an old dog new tricks
9. LED s life lessons The industry is changing and growing rapidly New standards are evolving Understand yourself and your requirements Communicate clearly and trust, but inspect Recognize that ultimately, there will be fewer players Pick a good partner and travel well
Thank you for the opportunity to share the journey!