Difference between the central and global FUV-NUV color. Galaxies with contamination or very large error bars (1σ interval on the central or global color larger than 1.2 mag) are indicated by a pale green circle. The dark blue symbols with error bars are all our other points, including indications from the visual inspection results (see Table 4 and text for details). In blue: obvious spiral structure (crosses); arcs (circles); strong asymmetries, shells, tails, or signs of merger (squares). The red circles indicate galaxies with the SDSS spectral subclass BROADLINE. The dashed lines indicates 0 (no color gradient) and the dotted line is a LOWESS fit to the dark blue points.