Relation between the observed IR-to-FUV luminosity (IRX) and the UV spectral slope (β) for the 129 galaxies of the Brown et al. (2014) sample. The colour of each symbol indicates the specific SFR, following the scale given by the colour bar to the right. The locus followed by resolved quiescent star-forming (respectively starburst) galaxies from Boquien et al. (2012; respectively Kong et al. 2004) is indicated by the blue (respectively orange) line.