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GRANITE TEXTURE CLASSIFICATION WITH GABOR FILTERS

The problem of classifying the visual appearance of natural stones, such as granite plates, represents, nowadays, an important demand in marble and granite industry. Companies which operate in the natural stones supply chain, usually have to guarantee the uniformity of the visual appearance of a batch of plates. Such kind of task is typically carried out by a skilled worker who decides about the pertinence of a plate to a given group. The development of an expert system capable of automatically executing such control, would introduce significant enhancement in natural stone industry. The realization of such a system, however, is a challenging problem, since the appearance of the plates may be very similar and classification may be difficult also to a human observer. Among the various techniques which have been proposed in literature, texture analysis has emerged as the leading approach to the classification of the visual appearance of natural textures. Gabor filtering has also been recognized as an important technique in texture classification, due to its capability of modeling the response of cortical cells devoted to the analysis of visual signals in mammals. In this work a classification procedure of granite texture based on Gabor filters is presented. The main objective is to evaluate the effectiveness of Gabor filtering and the influence of the related parameters in granite texture classification. Four groups of granite types, with similar visual appearance, have been considered and submitted to a classification procedure. The effects of the following aspects on the percentage of success in classification have been investigated: Gabor filters design, feature space design, distance type, value of k in thek − nn algorithm. The results are promising and suggest that texture classification based on Gabor filtering can be a viable approach to the evaluation of the visual appearance of granite stones.