1. A method of generating a texture-encoding descriptor for an image region comprising: a) filtering the image region by applying a derivative of a base filter to the image region to generate a response vector for each pixel in the image region; b) determining a proximity of each response vector to each of a set of base orientations and a magnitude of each response vector; c) determining an association of each response vector to each of the base orientations based on the proximity, the magnitude and a significance of the location within the image region from which the response vector was generated; and d) aggregating the associations of each response vector in the image region to each of the base orientations to generate the descriptor.