Method for reducing a light intensity of a projection device

A method for reducing a light intensity of a projection device, comprising:

• projecting information in the form of a visual representation onto a total area;
• emitting, using the projection device, multiple electromagnetic signals which are essentially imperceptible to an observer onto the total area;
• detecting, with the aid of the electromagnetic signals, the presence of an object situated in the light path between the projection device and the total area;
• and
• reducing the light intensity of the projection device if an object is detected in the light path, wherein:
• the multiple electromagnetic signals are emitted within the boundary of the total area;
• at least one subarea, which is relevant for an observer within the total area of the visually represented information, is user selectable;
• and
• when at least one relevant subarea is selected, the multiple electromagnetic signals are emitted within the boundaries of the at least one selected relevant subarea.