Determination of material

A method for determining a material in a cargo, the cargo comprising a first object made of a first material and a second object made of a second material, the method comprising:

• obtaining image data associated with an inspection image of the cargo, for at least two levels of radiation energy;
• obtaining equivalence data associated with mass equivalence of at least one of the first material and the second material with respect to a reference material, for the at least two levels of radiation energy, wherein the mass equivalence of a given material with respect to the reference material corresponds to a thickness of an object made of the reference material, associated with a same radiation transmission, in the inspection image, as a radiation transmission associated with a thickness of an object made of the given material;
• obtaining observation data based on the image data and the equivalence data;
• and
• determining at least one of the first material and the second material, based on the obtained observation data.