A characterization method for characterizing an article made of composite material having woven, braided, or sewn fiber reinforcement, the method including a determination step of using X-ray tomography to determine gray levels of at least a portion of the article, followed by an exploitation step of exploiting the gray levels to obtain information concerning the weaving by distinguishing between at least the free matrix and the threads of fibers mixed with the matrix, the threads being considered as being a material that is homogeneous.