The photo copier apparatus has a scanner 110 that provides input to an image processing system 120 and this provides output a laser writer system 130,131. This includes a first detector and a second detector. The scanner and image processors are connected to a control unit 180 and this is coupled to a document identification unit that has a memory 163 containing reference data. Any attempt to copy a protected document is prevented by inhibiting output. The detection arrangements may include microwave operation.
