Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but at lower illuminance with potential reductions in energy consumption. Consideration of experimental design was used to review 70 studies of spatial brightness. Of these, the 19 studies considered to provide credible evidence of SPD effects were used to explore metrics for predicting the effect of SPD but did not provide conclusive evidence of a suitable metric, in part because of incomplete reporting of SPD characteristics. For future work, these data provide an independent database for validating proposed metrics.

No abstract

An experiment was carried out to investigate spatial brightness at photopic levels under lighting of different spectral power distributions. One aim was to replicate the experiment reported in 1990 by Berman et al. demonstrating that light with a higher scotopic / photopic (S/P) ratio would be perceived as brighter. In addition, a third SPD was included to investigate gamut area and two additional procedures were employed to provide concurrent validity of the findings. It was concluded that while lighting of higher S/P ratio was brighter, the S/P ratio alone was insufficient to predict spatial brightness. A metric for the chromatic contribution is also needed, this being provided by gamut area in the current work.

Space perception is the ability to estimate the three-dimensional layout of our environment from the arrangement of individual objects, their location and size. While estimating every distance in the three-dimensional environment, the human visual system uses a number of physical cues and depth perception can be affected by a variety of factors; reflectance, colour, and texture. The main purpose of this study is to understand the effect of chromaticity combinations on depth perception. A forced-choice paired comparison test was used to evaluate distance differences between colour combinations created by chromatic light in background and coloured objects in front. The experiments indicated perceptual variations in-depth assessments between different participants, which needed to be taken into consideration. The findings suggest a significant effect of some colour combinations on depth perception.