Characterization of the anisotropy in color textures

Our approach deals with a modeling of the local spatial distributions of the variations of color. It is an extension to color textures of the Neighbouring Gray Level Dependence Matrices (NGLDM) introduced by Sun et al. [1] and completed by Berry et al. [2]. To our knowledge, this is the first time that this extension has been proposed. We will name these matrices NCDM: Neighbouring Color Dependence Matrices. This approach consists in estimating the dependences of colors between a pixel and its neighbours. These matrices, associated with an isotropic mask, characterize the textures [5]. We have chosen to use an anisotropic neighbourhood corresponding to the eight principal directions to seek the dominant directions in a color texture. NCDM matrices evaluate the homogeneity or the heterogeneity of the color distribution for each direction. The variations of the color shades are computed in uniform perceptual color spaces such as LAB and HSV. We have chosen the color space "L1 norm" introduced by Angulo, Hanbury and Serra [3, 4].