Reducing non-linear artifacts of multi-material objects in industrial 3D computed tomography

In computed tomography (CT) several physical effects reduce the quality of reconstructed CT images. Beside scatter, one major deterministic artifact is the beam hardening effect which arises due to the polychromatic character of the used X-ray spectrum and causes cupping and streak artifacts. In this paper, a method is proposed which allows correcting beam hardening artifacts in two and multi-component objects. Neither is it necessary to have any estimate or knowledge of the incident X-ray spectrum nor material characteristics like mass density or absorption coefficients. The method works without any reference measurements and uses the original projection images. Several two-material specimens of miscellaneous material combinations were tested and corrected to show the efficiency of the proposed method.