Photosensitivity, broadcast guidelines and video monitoring

In late 1997, Japan experienced a major public health incident in which many people were taken ill after watching an animation program on television. The cause was subsequently identified as photosensitivity or photosensitive epilepsy, and following detailed investigation of the phenomenon, broadcasters in Japan have jointly introduced guidelines in order to prevent a recurrence. This paper discusses the problem of photosensitivity and its causative factors, both in general and in relation to this particular incident. We focus on interactions between contemporary TV display technology and the human visual system which appear to have contributed significantly to the scale of this incident. We describe the content of the guidelines and an automatic video analyzer which has been developed and deployed by NHK in order to alert production staff to potential guideline violations in video material.