Benchmark B₄ extraction of filaments with getsf. Plotted are the one-sided (left and right) profiles D_{α|β}(r) of the filament surface densities ℱ_ƛY, their slopes γ_{α|β}(r), multiplied by 10²¹ for convenience, the reference line with a slope of −1, and the Gaussian beam with the half-maximum width O_H = 13.5″. The profiles represent the median densities along the skeleton and the vertical bars are their positive and negative deviations ς_{α|β}±(r) about the median profile. The left panel shows the true profiles of the simulated filament 𝒟_F across its crest. The middle panel presents the profiles, measured in the ℱ_ƛY component of 𝒟_13″ along the entire detected skeleton length (Fig. 13). The right panel displays the more accurate profiles, measured across the outermost skeleton loop, where the filament is least affected by the inaccuracies of its background.