Observed (gray) and best-fitting (green) He I 10830 Å triplet profiles corresponding to a typical penumbral profile (upper row) and a filament profile (lower row). The coordinates of each pixel on the map are indicated in the y-label. A shadowed green area is displayed indicating the range of solutions compatible with the profiles obtained with the method described in Sect. 5. In the left panels the parameters of the best fit are displayed. The symbol I_LC is the local continuum intensity.