A quantitative radiographic method uses X-ray imaging. The method uses a ratio of the absorption signal and the (small-angle) scattering signal (or vice-versa) of the object as a signature for the materials. The ratio image (dubbed R image) is independent from the thickness of the object in a wide sense, and therefore can be used to discriminate materials in a radiographic approach. This can be applied to imaging systems, which can record these two signals from the underlying object (for instance, an X-ray grating interferometer). Possible applications could be in material science, non-destructive testing and medical imaging. Specifically, the method can be used to estimate a volumetric breast density. The use of the R image and the corresponding algorithm are also presented hereafter.