  Recent advancements in propagation-based phase-contrast imaging, such as
hierarchical imaging, have enabled the visualization of internal structures in
large biological specimens and material samples. However, wavefront
marker-based techniques, which provide quantitative electron density
information, face challenges when imaging larger objects due to stringent beam
stability requirements and potential structural changes in objects during
longer measurements. Extending the fields-of-view of these methods is crucial
for obtaining comparable quantitative results across beamlines and adapting to
the smaller beam profiles of fourth-generation synchrotron sources. We
introduce a novel technique combining an adapted eigenflat optimization with
deformable image registration to address the challenges and enable quantitative
high-resolution scans of centimeter-sized objects with micrometre resolution.
We demonstrate the potential of the method by obtaining an electron density map
of a rat brain sample 15 mm in diameter using speckle-based imaging, despite
the limited horizontal field-of-view of 6 mm of the beamline (PETRA III, P05,
operated by Hereon at DESY). This showcases the ability of the technique to
significantly widen the range of application of wavefront marker-based
techniques in both biological and materials science research.
