Evaluating Luminance Uniformity Metrics Using Online Experiments

Luminance uniformity of luminaires is an important design aspect that can affect perceived discomfort glare, luminaire efficiency, and visual satisfaction. There is, however, a lack of studies that evaluated the performance of different luminance uniformity metrics. This article presents results of two studies where luminance patterns were presented via online questionnaires and subjective ratings of uniformity were collected. Study 1 examined the performance of a uniformity metric based on the human visual system (UHVS) using a priori hypotheses, whereas Study 2 compared UHVS to four other metrics: Max:Min, Avg:Min, entropy uniformity (EU), and coefficient of variation (CV) using correlations and non-linear models. Of the metrics evaluated, UHVS performed best for predicting perceived luminance uniformity. In situations where a tradeoff between metric calculation simplicity and performance is acceptable, the use of CV is recommended.