Digital and Analog Enhancement Techniques

Digital and analog units for enhancing video signals and images are often regarded as competing with each other. There is no point in setting them up as adversaries, but the criteria for selecting one approach over the other should be understood. Analog enhancement is to be preferred when the required signal processing is simple and straightforward and when cost is a primary constraint. Even the simplest digital enhancement systems, however, cost as much as moderately expensive analog systems, so their use is generally reserved for complicated operations, such as those requiring long delay times, where analog systems do not perform well. It is recognized that this situation is changing as analog technology develops (CCDs and diode arrays, for example) and as digital components get cheaper. Stand-alone systems will be more expensive than those included in other devices whether they are analog or digital. Finally, when all the constraints are taken into account (particularly the required performance characteristics and money available), it can be decided whether the proper approach is analog, digital or hybrid.