1. A computer-implemented method for processing radiographic images by extrapolating a two-dimensional mask M θ2 from a series of two-dimensional masks, the method comprising: at a radiographic device comprising an X-ray source and a digital detector that is in planar arrangement opposite the source and which has a limit (d, d′): a) recording a series of images at a series of positions S γ for the X-ray source of a volume of interest consisting of an object located between the X-ray source and the digital detector; b) calculating a series of two-dimensional masks M γ from the series of images, the series of two-dimensional masks M γ associated with the series of positions S γ for the X-ray source, located between a first position S θ1 and a second position S θ2 for the X-ray source, starting from a first two-dimensional mask M θ1 and a second two-dimensional mask M θ2 ; c) calculating an intermediate three-dimensional mask for the object, starting from the series of two-dimensional masks M θ and the first two-dimensional mask M θ1 and the second two-dimensional mask M θ2 ; d) extrapolating the second two-dimensional mask M θ2 beyond the limits d or d′ of the digital detector, according to a relative position between the first position S θ1 and the second position S θ2 , starting from the intermediate three-dimensional mask; and e) reconstructing a final three-dimensional digital mask from a resulting series of extrapolated two-dimensional masks M θ2 .