Visual Fatigue When Viewing Stereoscopic Television with Binocular Parallax

Abstract

Stereoscopic 3-D television broadcasting services are expected to underpin the imaging environments of the future, but several problems must still be solved before 3-D television can enter widespread, popular use. Visual fatigue stands out as the most important of these. With present systems, an audience of several hundred at the 3-D theater of an amusement park, for instance, complains of visual fatigue after watching 3-D images for only 10–20 min. If the same were to happen after only a couple of hours with a 3-D TV broadcasting service, the consequences and very feasibility of the service would necessarily come into question. Even if the effects on human health are not serious enough to require medical assistance, no broadcasting service that causes many viewers to suffer from visual fatigue could be accepted. It is, therefore, essential to devise a system prior to implementation that enables a large number of viewers with differing characteristics to watch 3-D TV under various viewing conditions for long periods without apparent visual fatigue. Unlike viewers of conventional TV, the viewers of 3-D TV make full use of binocular stereopsis function and are, therefore, liable to experience visual fatigue. Here, we examine characteristics of visual fatigue due to binocular stereopsis and consider possible solutions.

Issues for the Evaluation and Elimination of Fatigue.

The key challenges for evaluating fatigue are:

• 1. The subjectivity of fatigue, which cannot be measured directly. It is necessary to establish an objective index.

• 2. The broadness of the term, which allows considerable diversity and ambiguity of interpretation. This diversity and ambiguity has to be excluded.

• 3. Identifiable causes of visual fatigue, such as visual dysfunction and disease, can be reduced or eliminated by the ophthalmologist but viewers often complain of visual fatigue for no identifiable reason.

The following solutions are proposed in this chapter:

• 1. Fatigue studies in labor and other sectors have been based on the view that any change in bodily functions under load reflects fatigue. They measure functional deterioration, so deterioration of visual function becomes the marker of visual fatigue. In this study, we use the state of visual functioning observed directly before and after viewing binocular parallax-based 3-D TV as our objective index.

• 2. This study considers only visual fatigue, not fatigue in general.

• 3. If visual fatigue during and after viewing 3-D TV is due to visual malfunction or disease, it is regarded as a matter for medical treatment and is disregarded here. We also disregard fatigue due to indefinable causes, limiting our study of visual fatigue in this chapter to fatigue that has identifiable causes.