A display apparatus comprising a screen for displaying information to a viewer and illumination means for illuminating the screen , the apparatus further comprising: directional detecting means for detecting electromagnetic radiation incident on the apparatus ; and control means configured to control the illumination means in dependence on the detected direction of incidence of the electromagnetic radiation; wherein the directional detecting means comprises a plurality of electromagnetic radiation-sensing means , disposed around the apparatus or the screen thereof; and wherein the directional detecting means is adapted to ascertain the direction from which the electromagnetic radiation is incident on the detecting means by at least two directional parameters of the incident electromagnetic radiation, the said at least two directional parameters including (i) an angle of incidence between the incident electromagnetic radiation rays and a normal to the detecting means or a reference plane containing the detecting means, and (ii) an azimuth angle of the incident electromagnetic radiation rays relative to a reference axis defined by the detecting means or the screen ; and wherein the screen is a bidirectionally or multidirectionally viewable screen, in which different images, or given images of different brightnesses or intensities, are generated for viewing from at least two different viewing directions or angles relative to the screen , and the control means is configured such that the brightness or intensity of the information displayed along the at least two different viewing directions is determined and controlled independently in dependence on the detected direction of incidence of the electromagnetic radiation. directional detecting means for detecting electromagnetic radiation incident on the apparatus ; and control means configured to control the illumination means in dependence on the detected direction of incidence of the electromagnetic radiation; wherein the directional detecting means comprises a plurality of electromagnetic radiation-sensing means , disposed around the apparatus or the screen thereof; and wherein the directional detecting means is adapted to ascertain the direction from which the electromagnetic radiation is incident on the detecting means by at least two directional parameters of the incident electromagnetic radiation, the said at least two directional parameters including (i) an angle of incidence between the incident electromagnetic radiation rays and a normal to the detecting means or a reference plane containing the detecting means, and (ii) an azimuth angle of the incident electromagnetic radiation rays relative to a reference axis defined by the detecting means or the screen ; and wherein the screen is a bidirectionally or multidirectionally viewable screen, in which different images, or given images of different brightnesses or intensities, are generated for viewing from at least two different viewing directions or angles relative to the screen , and the control means is configured such that the brightness or intensity of the information displayed along the at least two different viewing directions is determined and controlled independently in dependence on the detected direction of incidence of the electromagnetic radiation. <EOS>