DHP images collected from Alto Tajo and Cuellar in Spain.

Digital Hemispherical Photography images taken in 33 30 x 30 m plots across two sites in Spain. Images were taken on a 10 m grid, making 16 locations per plot (see Flynn et al., 2022 for details). At each location, DHP images were captured with three exposure settings (automatic and ± one stop exposure compensation), levelling a Canon EOS 6D full frame DSLR sensor with a Sigma EX DG F3.5 fisheye lens, mounted on a Vanguard Alta Pro 263AT tripod. For each RGB image, the blue band was extracted, as this best represents sky/ vegetation contrast. For each plot, an exposure setting was chosen based on visual assessment and pixel brightness histograms of four images indicative of the whole plot. Automatic thresholding was carried out using the Ridler and Calvard method (1978), creating a binary image of sky and vegetation.