Comparison of imaging and spectral data. a: composite image built using grz DECaLS data. b: GALEX color image retrieved using the Legacy Survey cutout service. c: g − r color map constructed based on the DECaLS data. d: stellar continuum level at 5500 ± 20 Å in the rest frame along the slit. The zero point is chosen to have zero magnitude at the center of the galaxy. e: emission line fluxes recovered from the long-slit spectra. Color stripes are shown for reference and comparison with other figures and represent emission-line peaks at the inner star forming ring R = ±18″, external diffuse emission region at R = 45″ − 75″, and the galaxy nuclear and emission enhancement at R = −10″.