Reading comfort in relation to monitor and ambient luminance levels: A study using continuous rating scale and paired comparison methodology

In this work, it is investigated how reading comfort is influenced by monitor and ambient luminance levels, when employing high-luminance monitors. High-luminance monitors can be used to get more light on the eye and elicit non-image-forming effects. However, this might lead to reduced reading comfort. Two psychophysical methods, a continuous rating scale and paired comparison, were employed to investigate reading comfort in relation to the luminance of the monitor and the ambient environment. The results of 18 observers for the continuous rating scale experiment (aged 20 y to 30 y) and 20 observers for the paired comparison experiment (aged 20 y to 37 y) indicate that reading comfort is significantly influenced by both monitor and ambient luminance levels The paired comparison methodology provided more distinctive capabilities and thus offered a deeper insight. In contrast to prior work suggesting a linear relation between monitor luminance and preferred ambient luminance, the current results indicate that the reading comfort level reaches a tipping or saturation point. A monitor luminance level of 260 cd m−2 combined with an ambient luminance level of 68 cd m−2 provided the highest reading comfort. This reading comfort could not be matched when employing a higher monitor luminance level of 700 cd m−2.