TY - JOUR
T1 - A Test of the S/P ratio as a correlate for brightness perception using rapid-sequential and side-by-side experimental protocols
AU - Houser, K. W.
AU - Fotios, S. A.
AU - Royer, M. P.
N1 - Funding Information:
This project was made possible by Project CANDLE partners: Cooper Lighting, Erco Lighting, Fisher Marantz Stone, Gabriel Mackinnon, Horton Lees Brogden Lighting Design, I2 Illuminations, IALD Education Trust, Lighting Design Alliance, Litecontrol Corporation, Lutron Electronics, Naomi Miller Lighting Design, Office for Visual Interaction Inc, Penn State University, Philips Lighting Company, Philips SSL Solutions, Randy Burkett Lighting Design, Schuler Shook, and the US Department of Energy (under PNNL Contract Number 79894). Litecontrol is gratefully acknowledged for the donation of the luminaires, Lumileds for the donation of the LEDs, and Lighting Science Group Corporation for the development of the control system hardware and software. Many thanks to Jamie Devenger, Luke Renwick, and Dan Moynagh for assisting with the apparatus and for their help with running the subjects.
PY - 2009/10
Y1 - 2009/10
N2 - An experiment was performed to: 1 Test the hypothesis that the ratio P*(S/P)0.5 can be used to predict the perception of spatial brightness, and 2) directly compare the rapid-sequential and side-byside evaluation modes for assessing spatial brightness. The two evaluation modes produced comparable results. Though the side-byside method has in the past been questioned by others, the data herein illustrates that it is neither faulty nor invalid. Red, green, and blue LEDs were employed to create four light settings that were permutations of two S/P ratios (1.7 and 2.6) and two luminance levels (24 and 30 cd/m2). The S/P ratios corresponded to the practical extremities of CCT (2900 and 7200 K) and were structured to have their chromaticity on the blackbody locus. At equal luminance there was no difference in the perception of brightness, irrespective of CCT. At unequal luminance, but when the ratio of P*(S/P)0.5 was set to 1:1, brightness perception was predicted by luminance. These data suggest that spatial brightness perceptions at photopic light levels are unrelated to the S/P ratio of the illumination. These results are consistent with the "prime color" theory of vision that is rooted in the trichromatic nature of human vision.
AB - An experiment was performed to: 1 Test the hypothesis that the ratio P*(S/P)0.5 can be used to predict the perception of spatial brightness, and 2) directly compare the rapid-sequential and side-byside evaluation modes for assessing spatial brightness. The two evaluation modes produced comparable results. Though the side-byside method has in the past been questioned by others, the data herein illustrates that it is neither faulty nor invalid. Red, green, and blue LEDs were employed to create four light settings that were permutations of two S/P ratios (1.7 and 2.6) and two luminance levels (24 and 30 cd/m2). The S/P ratios corresponded to the practical extremities of CCT (2900 and 7200 K) and were structured to have their chromaticity on the blackbody locus. At equal luminance there was no difference in the perception of brightness, irrespective of CCT. At unequal luminance, but when the ratio of P*(S/P)0.5 was set to 1:1, brightness perception was predicted by luminance. These data suggest that spatial brightness perceptions at photopic light levels are unrelated to the S/P ratio of the illumination. These results are consistent with the "prime color" theory of vision that is rooted in the trichromatic nature of human vision.
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U2 - 10.1582/LEUKOS.2009.06.02003
DO - 10.1582/LEUKOS.2009.06.02003
M3 - Article
AN - SCOPUS:77649215041
SN - 1550-2724
VL - 6
SP - 119
EP - 137
JO - LEUKOS - Journal of Illuminating Engineering Society of North America
JF - LEUKOS - Journal of Illuminating Engineering Society of North America
IS - 2
ER -