Images of the epoxy sections were obtained with a microscope (Nikon 90i) equipped with a Nikon DS digital camera. For each section, four partly overlapping digital images were recorded and combined into one 24‐bit colour image using analySIS (version 3.2, Soft Imaging System).
All images were aligned by a custom‐made computer program running on Linux (openSUSE 11.2, www.opensuse.org) as previously described in detail (Chang et al., 2015 (link)). The final image size was 2700 × 2000 pixels with an isotropic pixel size of 0.93 μm.