Maps of the Hα flux, binning scheme, and key line ratios for individual spaxels and after Voronoi binning in NGC 4535. a) Map of log(Hα/10⁻¹⁷ erg s⁻¹ cm⁻² arcsec⁻²), at the native 0.2″ single-spaxel resolution. The circular areas that appear white in this and other panels are locations of masked foreground stars. b) Map of log([S II]/Hα) at single-spaxel resolution. White areas have S/N < 3 for the relevant emission lines. The black contour corresponds to Σ_Hα = 8 × 10⁻¹⁷ erg s⁻¹ cm⁻² arcsec⁻² or about a 16σ detection for Hα. c) Same as b) but for the log([O III]/Hβ) ratio. d) Representation of the Voronoi binning scheme adopted to recover the low-surface-brightness line emission in the DIG, as described in the text. Each bin is assigned a random colour. e) Map of log([S II]/Hα) using the binned data. f) Same as e) but for the log([O III]/Hβ) ratio.