2D Systems Theory and Applications

In the case of a continuous signal, the independent variables range over a continuum of values where, for example, the intensity I .x; y/ of a photographic image is a 2D continuous signal. Discrete signals, however, can be modeled as a function defined only on a set of points, such as the set of integers. Mixed signals can be modeled as a function of some continuous and some discrete variables. Lim1 presents a compact source of further examples of continuous and discrete signals. Rogers and Owens2 give a detailed treatment of differential linear repetitive processes which are naturally defined in terms of mixed signals.