A method for characterizing an object , comprising: a) placing the object between a radiation source and a radiation detector , the radiation source being configured to emit an X or gamma ionizing electromagnetic radiation that propagates to the object; b) irradiating the object with the radiation source and detecting radiation transmitted by the object using the radiation detector, the radiation detector comprising a plurality of pixels (30 i ), each pixel (30 i )being associated with one portion (20 i ) of the object; c) for each pixel (30 i ), forming an energy spectrum ( S i ) of the detected radiation, each spectrum comprising at least two distinct energy bands; d) from each spectrum formed in c), estimating, in each pixel, at least two equivalent thicknesses ( L̂ i , 1 ... L̂ i,M , L̂' i, 1 ... L̂ ' i,M ) respectively associated with at least two basis materials ( mat 1 ... mat M , mat' 1 ... mat' M ); wherein the method comprises, following d): e) from the equivalent thicknesses resulting from d), calculating a structural parameter of the object in various pixels, the structural parameter of the object ( P i ) being for each pixel (30 i ): - a thickness (L i ) of that portion of the object (20 i ) which is associated with the pixel; - or representative of a composition of that portion of the object (20 i ) which is associated with the pixel. f) spatially smoothing the structural parameter calculated in a plurality of pixels, so as to associate, with each pixel, a smoothed structural parameter P i ∗ ; g) from the structural parameter smoothed in each pixel, and from each spectrum formed in c), estimating, in each pixel, regularized equivalent thicknesses L ^ i , m = 1 | P i ∗ ... L ^ i , m = M | P i ∗ , L ^ ′ i , m = 1 | P i ∗ ... L ^ ′ i , m = M | P i ∗ respectively associated with each basis material; h) characterizing the object from the regularized equivalent thicknesses estimated in g). a) placing the object between a radiation source and a radiation detector , the radiation source being configured to emit an X or gamma ionizing electromagnetic radiation that propagates to the object; b) irradiating the object with the radiation source and detecting radiation transmitted by the object using the radiation detector, the radiation detector comprising a plurality of pixels (30 i ), each pixel (30 i )being associated with one portion (20 i ) of the object; c) for each pixel (30 i ), forming an energy spectrum ( S i ) of the detected radiation, each spectrum comprising at least two distinct energy bands; d) from each spectrum formed in c), estimating, in each pixel, at least two equivalent thicknesses ( L̂ i , 1 ... L̂ i,M , L̂' i, 1 ... L̂ ' i,M ) respectively associated with at least two basis materials ( mat 1 ... mat M , mat' 1 ... mat' M ); e) from the equivalent thicknesses resulting from d), calculating a structural parameter of the object in various pixels, the structural parameter of the object ( P i ) being for each pixel (30 i ): - a thickness (L i ) of that portion of the object (20 i ) which is associated with the pixel; - or representative of a composition of that portion of the object (20 i ) which is associated with the pixel. - a thickness (L i ) of that portion of the object (20 i ) which is associated with the pixel; - or representative of a composition of that portion of the object (20 i ) which is associated with the pixel. f) spatially smoothing the structural parameter calculated in a plurality of pixels, so as to associate, with each pixel, a smoothed structural parameter P i ∗ ; g) from the structural parameter smoothed in each pixel, and from each spectrum formed in c), estimating, in each pixel, regularized equivalent thicknesses L ^ i , m = 1 | P i ∗ ... L ^ i , m = M | P i ∗ , L ^ ′ i , m = 1 | P i ∗ ... L ^ ′ i , m = M | P i ∗ respectively associated with each basis material; h) characterizing the object from the regularized equivalent thicknesses estimated in g). <EOS>