Images of a focused monochromatic (12 keV) beam as measured at bending-magnet beamline B16 (DLS, UK). Top row: a raw unprocessed XBI image obtained using a 200 µm circular aperture, L/D = 3 and counting time of 0.5 s (left); corresponding reconstructed beam cross-section image (centre); reference direct image taken with an X-ray Eye camera set up 20 cm downstream and near the focal point (right). Bottom row: a raw XBI image obtained using a cross aperture with slit size of 1700 µm × 25 µm, L/D = 3 and counting time of 1 s (left); corresponding reconstructed beam cross-sectional image (centre); beam cross-sectional image reconstructed from an image obtained by averaging ten raw XBI images (right). Beam cross-sectional images were reconstructed using 16 Lucy–Richardson iterations. Other XBI parameters: 125 µm Kapton foil, α = 25°, noiseless Medipix-2 detector with 55 µm pixels (Llopart et al., 2002).