N-PDFs obtained from the various column density maps. Left: N-PDF of the high-res N_H column density map derived using all Herschel dust data employing method I. Right: N-PDF of the N_H column density map derived with method II. In solid red and dotted lines, the two-component log-normal fit is shown, whereas the power-law fits regimes are depicted in black dotted lines. The green lines show the N-PDF of H I. Here, m refers to the slope of the error tail for low column density, while α denotes the slope of the power-law tail for higher column densities. η is defined by $\eta =ln\frac{N}{⟨N⟩}$, where N is the column density and ⟨N⟩ the mean column density. μ and σ refer to the peak and width of the fitted log-normals, respectively. See Appendix E for more details.