The Dirac Delta function is often used in imaging. If you wish to analyze the performane of an imaging device, it is useful to measure the device's response to as simple an input as possible. The delta function (or, in real life, an approximation to the delta function), is often used as the simplest possible input for an imaging device:
Mathematically, the delta function is defined in terms of the following properties:
Douglas J. Wagenaar, Ph.D., wagenaar@nucmed.bih.harvard.edu