Most of the new results that have been obtained recently in optical pattern recognition outperform the classical optical correlation approaches. Three kinds of approaches exist in filtering technics for pattern recognition. It can lead to interesting, but generally misunderstood, methods. In contrast, the theoretical approach consists in minimizing the probabitity of errors. In order to apply this approach, a large a priori knowledge is necessary which is not always available for real problems.
Heuristic methods constitute a third approach.
This work clearly belongs to the class of heuristic methods. It has allowed us to obtain more robust methods than the classical theoretical ones, and to better understand some empirical approaches, but futher work is required to characterize them in greater detail.