  The purpose of this paper is to present a complete methodology based on a
multidisciplinary approach, that goes from the extraction of features till the
classification of a set of different portuguese granites. The set of tools to
extract the features that characterise polished surfaces of the granites is
mainly based on mathematical morphology. The classification methodology is
based on a genetic algorithm capable of search the input feature space used by
the nearest neighbour rule classifier. Results show that is adequate to perform
feature reduction and simultaneous improve the recognition rate. Moreover, the
present methodology represents a robust strategy to understand the proper
nature of the images treated, and their discriminant features. KEYWORDS:
Portuguese grey granites, feature extraction, mathematical morphology, feature
reduction, genetic algorithms, nearest neighbour rule classifiers (k-NNR).
