Signal, Image and Optical Processing - Much of the data computers have to deal with comes in the form of signals that have to be processed to give some output for the user. Examples might be audio signals from a microphone or water temperature as read by a thermometer in a river. Such signals can be processed to extract information or enhance certain things (e.g is the noise too loud or the river freezing?). An important type of signal are the two-dimensional images produced by cameras. These have a range of special techniques to extract information from still or video images(e.g. for recognising faces). Further techniques deal with 3D optical holograms.