Figure 1

A rapidly acquired STXM map (a) (80 µm × 80 µm, 50 × 50 pixels, 20 ms dwell time/pixel, scale bar = 20 µm) is used to create a mask (c) which is dense only in the regions of interest (green areas in b). A sub-sampled sparse XRF acquisition (e) is approximately 3 times faster than a full one (d). When the sparse acquisition is reconstructed through biharmonic in-painting (f) it can be processed with the usual XRF workflows producing similar results. In this specific case Panels d, e and f show Si XRF signal collected at 1.95 keV on a foraminifera section over an area of 80 µm × 80 µm, with 1.6 µm step size and 3 s acquisition time/pixel.