Fractal signatures for complex natural textures recognition

Random textures can be considered fractal sets under certain circumstances. The main parameter of a fractal set is its dimension. The description of the fractal dimension over the spatial scale is called fractal signature. Some methods for defining the fractal dimension are described, with special emphasis on the Hausdorff and box counting. Fractal signatures are defined based on two viewpoints: upside view, from the brightest pixels, and downside view, for the darkest ones. Signatures´ geometry is compared for different textures. Natural images are taken as fractals, and their signatures evaluated as features for texture recognition. Cork-agglomerated images with defects, and patches of office and CRAFT paper images were taken as fractal sets and their signatures were analysed. Results were discussed and some conclusions were drafted