1 To translate graphical information into a series of numbers suitable for processing by (digital) computer. For example, topographic detail can be taken from a map and digitized to produce a computer-generated topographic cross-section. The superimposition of an orthogonal coordinate system on to an image and the recording of the data in a machine-readable form assumes that a two-dimensional image is being analysed. It can be done three- dimensionally if stereophotographs are analysed. Fully automated systems also exist for this type of work.
2 To convert analog data into digital form by sampling the continuous record at discrete sample intervals. See also aliasing; and sampling frequency.