Computer vision deals with the problem of manipulating information
contained in large quantities of sensory data, where raw data emerge
from the transducing 6 7 sensors at rates between 10 to 10 pixels per
second. Conventional general- purpose computers are unable to achieve
the computation rates required to op- erate in real time or even in near
real time, so massively parallel systems have been used since their
conception in this important practical application area. The development
of massively parallel computers was initially character- ized by efforts
to reach a speedup factor equal to the number of processing elements
(linear scaling assumption). This behavior pattern can nearly be
achieved only when there is a perfect match between the computational
struc- ture or data structure and the system architecture. The theory of
hierarchical modular systems (HMSs) has shown that even a small number
of hierarchical levels can sizably increase the effectiveness of very
large systems. In fact, in the last decade several hierarchical
architectures that support capabilities which can overcome performances
gained with the assumption of linear scaling have been proposed. Of
these architectures, the most commonly considered in com- puter vision
is the one based on a very large number of processing elements (PEs)
embedded in a pyramidal structure. Pyramidal architectures supply the
same image at different resolution lev- els, thus ensuring the use of
the most appropriate resolution for the operation, task, and image at
hand.