Distribution of the gas-phase metallicities of our sample of star-forming spaxels against their stellar mass surface densities. The hexagonal bins depict the sample distribution with darker colors corresponding to a denser region of data points. The corresponding fitting result for our data within a mass range of 6.87 ≲ log Σ_∗ (M_⊙ kpc⁻²) ≲ 8.33, which is defined as the range that covers 80% of the data, was computed via Eq. (7) from Sánchez et al. (2013) and is shown as a red line. The gray errorbar in the top left corner shows the average uncertainties in gas-phase metallicity and Σ_*. FADO only gives errors based on the goodness of the fit, stellar mass errors are very small, and the average Σ_* is not visible within this plot.