In rooms with frequent use of slide projectors, writing projection devices or video projectors, the general lighting must feature a control mode for note-taking lighting, the level of which is not specified and depends strongly on the individual case, e.g. the brightness of the projected image. Darkening and brightening should be realised within 3 to 10 seconds. On vertical image projection surfaces, the vertical illuminance Ev should not be more than 10% of the reduced horizontal illuminance Eh, which can be realised using narrow-distribution luminaires in the projection surface area.