For a subsample of S⁴G galaxies, comparison between the pitch angles determined with Fourier methods (from this work, see text) and (a) mean pitch angle, (b) inner mean pitch angles, and (c) mean pitch angle weighted by the arc length of the segments. We show measurements with very reliable (=1, filled circle) and acceptable (=2, empty diamonds) flags in Herrera-Endoqui et al. (2015). As in Fig. 5, the red dashed line corresponds to the straight line y = x, while the green dotted line shows the linear fit to the cloud of points.