Brightness in Cinema: When is it too bright?

Recent advances in display technologies enable home and cinema display systems to reach higher peak luminance and perceived Full Screen White (FSW) levels while also improving on black level capabilities. This next generation of imaging technology will help creators deliver content of higher visual quality, increasing the overall Quality of Experience (QoE) of viewers. However, there is growing concern in the cinema industry that possible “mismanagement” or “misuse” of the new luminance capabilities may result in viewers' visual discomfort. A typical example of potential “misuse” is abrupt temporal brightness transitions during a scene change or even within the same scene. Prior studies, which were conducted in home environments, reported that displaying a higher amount of light could potentially lead to viewers' visual discomfort. However, no study has been conducted in cinema environment. In this work, we quantify the human observer tolerance to temporal brightness transitions in a cinema environment by performing four subjective experiments. The different experiments evaluate the impact of various distributions of light on screen, namely full screen, highlights, noise and real images. Results of the experiments indicate that the light distribution as well as the peak luminance values have minimum impact on viewers' tolerance of temporal brightness transitions. Indeed, observers reported visual discomfort only when the total amount of light on screen varied significantly. Specifically, for average on-screen luminance equal to both 0.1 or 1 cd/m
²
, viewers rated as “slightly annoying” and “annoying” transitions to average on-screen luminance as low as 35 cd/m
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and 75 cd/m
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respectively. It is to be noted that viewers reported visual discomfort at a similar transition intensity for both saturated colors and white. The results of our study could provide useful insight to content creators, for example providing a warning that temporal transitions may cause visual discomfort.