Spectral curvature maps of the central region of Abell 1775. Left: Spectral curvature map of high-resolution radio images (6″ × 6″). Right: Spectral curvature map of low-resolution radio images (15″ × 15″). Both maps are three-frequency SC maps between 144 MHz and 650 MHz. Contour levels are drawn at [ − 1, 1, 2, 4, 8, 16...] × 3σ_rms of the LOFAR image at 15″ resolution. The diverging colour bar shows the SC from −2 to 2, where the white colour is when SC = 0.