Two-dimensional application of on CALIFA IFS data for the star-forming galaxy NGC 3991. a) True-color SDSS image composite; b)–d) surface brightness maps (mag/Λ″) computed by spaxel-by-spaxel convolution of the r-band filter transmission curve with the observed spectrum (μ_obs; panel b), the best-fitting stellar SED to the observed spectrum (μ_fit; panel c)), and after removal with of stellar and nebular emission associated with ongoing or recent (≤30 Myr) star formation (μ(OBS-30 Myr); panel d)). Subtraction of the latter from μ_obs yields the μ enhancement (in mag) owing to the recent SF (panel e)), which shows a close spatial correlation with the Hα flux (in log 10^-16 erg s^-1 cm^-2; panel f)) and Hα equivalent width (in Å; panel g)).