Upper panels: HST/NICMOS 1.6   μm to 1.1μm flux ratio maps. Dark regions show a deficit of 1.1   μm flux, that is, a redder F160W−F110W color. All three galaxies are shown on the same flux ratio scale. Lower panels: the contours are the observed Hα fluxes of the three galaxies for which extracted spectra of circumnuclear H ii regions. For each galaxy we show the regions of interest: the nucleus (defined as the peak of the 6200 Å  continuum emission, light blue dots), bright H ii regions (red, blue, purple, and green dots). The orange dots are the spaxels used to produce the average spectrum of regions with relatively low EW of Hα (see Sect. 2.3). For NGC 7771 we additionally extracted a spectrum of the possible location of the true nucleus (shown as a black dot), based on the Hα velocity field (see Paper I for details).