1. In a projection system comprising a projector to project an image for display on a background and at least one camera to capture an image of said background, said at least one camera having a viewpoint differing from the viewpoint of said projector, a method of inhibiting a subject's eyes from being exposed to projected light when the subject is positioned in front of the background, said method comprising: capturing the image of the background including the displayed image; processing the captured image to detect the existence of a subject therein and to locate generally the subject; and masking image data used by the projector to project the image corresponding to a region that encompasses at least the subject's eyes, said image data masking compensating for said differing camera and projector viewpoints.