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Proceedings Paper

Psychophysical evaluations of various color rendering from LED-based architectural lighting
Author(s): Maria Thompson; Una-May O’Reilly; Robert Levin
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Paper Abstract

This paper reports a study on visual evaluation of colors under LED lighting operated by an energy-saving control strategy. Digitally controlled LED systems can produce various qualities of light, adjustable to users' requirements. In this context, a novel control concept inspired this research: strategic control of Red, Yellow, Green & Blue LEDs forming white light can further increase energy efficiency. The resulting (more efficient) light, however, would have decreased "color rendering" (ability of accurately reproduce colors). The notable point is that while reducing color rendering, color temperature and light levels can stay constant and hence the appearance of the modified light could stay the same, and only the colors of illuminated objects would change. But how spaces would be perceived under such light with changing color rendering is a key question. This research investigated the hypothesis that a significant range of color distortions would be unnoticeable under such dynamically controlled illumination, especially outside of users' main field of view. If successful, such control technique could be implemented for unoccupied spaces that would not tolerated dimming, and minimize peak hours energy waste, potentially enabling significant power reductions. Three incremental series of experiments were performed based on subjective assessment of colors under changing color rendering. Tests were carried out for central and peripheral vision, using laboratory booths (phase 1) and full scale architectural mockups (phase 2). Results confirmed the fundamental hypothesis, showing that the majority of subjects did not detect the color changes in their periphery while the same color changes were noticeable with direct observation.

Paper Details

Date Published: 14 September 2007
PDF: 12 pages
Proc. SPIE 6669, Seventh International Conference on Solid State Lighting, 66690Y (14 September 2007); doi: 10.1117/12.746759
Show Author Affiliations
Maria Thompson, Osram Sylvania (United States)
Una-May O’Reilly, Massachusetts Institute of Technology (United States)
Robert Levin, Osram Sylvania (United States)

Published in SPIE Proceedings Vol. 6669:
Seventh International Conference on Solid State Lighting
Ian T. Ferguson; Nadarajah Narendran; Tsunemasa Taguchi; Ian E. Ashdown, Editor(s)

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