Improving Micro-CT accuracy on feature extraction through image upscaling

X-ray Micro-CT is a technique of choice for the investigation of the internal features of materials. One typical necessary compromise is the choice of the resolution vs the size of the field of view. Cellular morphology analysis of foams can benefit from Micro-CT because both physical (low and high strain rate mechanical properties) and functional properties (fluid transport through cells, thermal and acoustical insulation) are strongly affected by the morphological parameters (strut sections area and shape, degree of cell inter-connections and distribution of cell interconnections diameters). The typical resolution of detectors commonly available is not able to provide an accurate 3D description of the real spatial distribution of the finest structural features. A new approach is proposed based on the upscaling of reconstructed slices, which is able to recover details from low resolution images and to minimize the morphological feature loss. In order to show the advantages of the proposed method, a phase contrast micro-tomographic acquisition was performed on a 10 mm wide polyurethane foam sample at the SYRMEP beamline at the Elettra - Sincrotrone Trieste (Italy) facility. Results from the standard workflow (slice stacking, slice filtration, thresholding) were compared to those from the new approach (slice stacking, slice upscaling, thresholding, binary volume comparison). The image upscaling allowed a reduction of the image noise without using heavy noise reduction filters and preserved finer details of the microstructure with respect to those from the conventional procedure.