Pixel-by-pixel relation between log T_dust and logΣ_dust according to Eq. (7) for two sample galaxies (NGC 3621 and NGC 5055). Blue points represent the mean values within each bin, with error bars indicating the standard deviation in each bin. The black line corresponds to the expected relation (see Eq. 7). The colour bar represents the galaxy radius. The sampled physical scale for each galaxy is quoted in its respective panel.