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Lookup NU author(s): Ruben PastilhaORCiD,
Dr Gaurav Gupta,
Professor Anya Hurlbert
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Temporal changes in illumination are ubiquitous; natural light, for example, varies in color temperature and irradiance throughout the day. Yet little is known about human sensitivity to temporal changes in illumination spectra. Here we aimed to determine the minimum detectable velocity of chromaticity change of daylight metamers in an immersive environment. The main stimulus was a continuous, monotonic change in global illumination chromaticity along the daylight locus in warmer (towards lower correlated color temperatures (CCTs)) or cooler directions, away from an adapting base light (CCT: 13000 K, 6500 K, 4160 K, or 2000 K). All lights were generated by spectrally tunable overhead lamps as smoothest-possible metamers of the desired chromaticities. Mean detection thresholds (for 22 participants) for a fixed duration of 10 seconds ranged from 15 to 2 CIELUV ΔE units, depending significantly on base light CCT and with a significant interaction between CCT and direction of change. Cool-changes become less noticeable for progressively warmer base lights and vice-versa. For the two extreme base lights, sensitivity to changes towards neutral is significantly lower than for the opposite direction. The results suggest a “neutral bias” in illumination change discriminability, and that typical temporal changes in daylight chromaticity are likely to be below threshold detectability, at least where there are no concomitant overall illuminance changes. These factors may contribute to perceptual stability of natural scenes and color constancy.
Author(s): Pastilha R, Gupta G, Gross N, Hurlbert A
Publication type: Article
Publication status: Published
Journal: Journal of Vision
Online publication date: 29/12/2020
Acceptance date: 26/10/2020
Date deposited: 16/12/2020
ISSN (electronic): 1534-7362
Publisher: Association for Research in Vision and Ophthalmology
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