Mode et orientation preferentielle de formes des granites par analyse d'images numeriques

(ENG) This study aims at the automatic determination of modes and shape preferred orientations (SPO) of the main phases of a granite. Numerical images of granite surfaces, previously treated by selective chemical colorations, are obtained by measuring the reflected light intensity using a CCD-camera and RGB filters. Automatic separation of phases, leading to modal analyses, is realized through multispectral classification. Determination of SPOs of the different phases can be performed without separation of the individual grains. An application is presented concerning the textures of the three main petrographic subtypes forming the granite pluton of Mont-Louis-Andorra (Eastern Pyrenees, France).