Recent innovative video technology enables us to use moving images with a variety of display systems, including large flat-panel displays and head-mounted displays; the proliferation of the latter has brought virtual reality into the spotlight. However, depending on the use of the images, undesirable biomedical effects such as visually induced motion sickness/VR sickness and visual fatigue may occur. To use images comfortably and safely, it is important to sufficiently consider these effects, i.e. image safety. This seminar introduces major findings for image safety as well as the current international guidelines based on these findings.