The notion of scale selection refers to methods for estimating
characteristic scales in image data and for automatically
determining locally appropriate scales in a scale-space
representation, so as to adapt subsequent processing
to the local image structure and compute
scale invariant image features and image descriptors.
An essential aspect of the approach is that it allows
for a bottom-up determination of inherent scales
of features and objects without first recognizing
them or delimiting alternatively segmenting them from their surrounding.
Scale selection methods have also been developed from
other viewpoints of performing noise suppression
and exploring top-down information.