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Shifting Our Vision for Lighting. Lux America 2012. Wendy Davis Associate Professor Director Illumination Design. Why do we light?. We do not light to: Expend / save energy To meet standards & building codes To meet budgets To use particular technologies.
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Shifting Our Vision for Lighting Lux America 2012 Wendy Davis Associate Professor Director Illumination Design
Why do we light? • We do not light to: • Expend / save energy • To meet standards & building codes • To meet budgets • To use particular technologies Image from: http://rabbishishler.blogspot.com.au/2012/02/soul-budget.html Image from: http://www.csiro.au/en/Outcomes/Energy/Saving-energy-in-your-home.aspx Image from: http://nyack-ny.gov/departments/building/
Why do we light? • We light so that people can see: • Books • Faces • Artwork • Stairways • Etc. Image from: http://www.autism-community.com/a-plethora-of-literacy-resources/ Image from: http://www.guardian.co.uk/world/2010/nov/25/ernest-cole-david-goldblatt-apartheid-photography Image from: http://www.optforhealthyliving.org/
Fixation with the incandescent lamp The ways we measure, evaluate and communicate about lighting are technology-focused & backward-looking Image from: http://cheaptalk.org/2011/03/18/backward-and-forward-looking-organizations/
Correlated colour temperature (CCT) + Duv - Duv
Colour rendering index (CRI) Reference illuminant Test source CIE Dxx Same CCT [K] Planckian (CCT<5000 K) Standard Daylight (CCT > 5000 K) #1 #2 #3 #4 #5 #6 #7 #8 Ra #9 #10 #11 #12 #13 #14
Colour rendering index (CRI) = perfect?
Colour rendering index (CRI) Neodymium incandescent lamp CRI = 77 (normal incandescent lamp CRI=100) Image from: http://www.ge.com/innovation/timeline/eras/breakthrough_discoveries.html Ref. LED
Colour rendering index (CRI) 3-LED Model Peaks at: 464, 538, 620 nm CRI = 63 Image from: http://glassbox-design.com/2009/elos-rgb-led-prototype-changes-colors-on-demand/ Ref LED
Further complications Hunt Effect Colorfulness / saturation increases with luminance
Moving beyond the incandescent Image from: http://www.eralight.biz/led-bulb/e27-led-bulb.html Image from: http://www.alibaba.com/product-gs/303496832/F96T12_replacement_LED_tube.html • Retrofits / replacement lamps: • Minimal consumer investment • Compatible with existing infrastructure • Reversible
Moving beyond the incandescent Image fromhttp://news.cnet.com/8301-11386_3-57428951-76/philips-led-replaces-100-watt-incandescent/ Image from: http://elektro-vault.blogspot.com.au/2012/06/27w-led-to-replace-100w-bulb.html • Retrofits / replacement lamps: • Difficult to engineer • Fail to capitalize on benefits of newer technologies • Presume incumbent technologies are optimal
Moving beyond the incandescent 1http://elearningfacultymodules.org/index.php/E-Learning_Terminology Disruptive technology “A new technology that changes the current way of approaching a particular problem or issue”1 Images from: Wikipedia Commons
Moving beyond the incandescent Let’s imagine… Image from: http://www.canstockphoto.com/illustration/imagine.html
How far could we go? Image from: http://www.cnet.com.au/apple-iphone-4-339303698.htm Image from: http://johngushue.typepad.com/blog/2010/06/technology.html Image from: Wikipedia Commons Image from: http://dekhomobile.blogspot.com.au/2011/11/latest-glass-mobile-phone-latest-mobile.html
How do we get there? Image from: http://www.guardian.co.uk/voluntary-sector-network/2012/jun/13/charity-conduct-strategic-review-advantages
Principle of Univariance • The cones transmit no spectral information • Countless different spectra can lead to identical patterns of cone activity • Perceptions of colour arise from combining and comparing the activity of the different cone classes
Colour matching functions x(λ) r(λ) y(λ) g(λ) z(λ) b(λ)
Colour matching functions • x + y + z = 1 • (x, y) is a 2-dimensional representation of chromaticity. • Y is a measure of visual intensity of light stimulus. • x, y, Y fully describe light stimulus.
Colour opponency Image from: http://facweb.cs.depaul.edu/sgrais/color_perception.htm
Colour opponency blue red red green yellow DeValois & DeValois (1993)
Moving beyond the incandescent Metamers
Luminous efficacy Luminous efficacy = radiant efficiency x luminous efficacy of radiation (LER) LER = 154 lm/W LER = 408 lm/W
Colour rendering Four lasers Image from: Wikipedia Commons
Object reflectance Image from: http://greatfruitpictures.onsugar.com/Orange-Fruit-Picture-18993899
Visual processing blue red red green yellow DeValois & DeValois (1993)
Moving forward • Spectral design & colour properties • Size & shape of lighting products • Spatial distribution of light • Modes of control & human interaction • … Image from: http://gooddisruptivechange.com/why-change-your-mindset/