Stokes profiles at the five representative spatial points indicated in Fig. 1. The profiles computed in LTE, 1D NLTE, and 3D NLTE are indicated in purple, black, and orange, respectively. In the first column, the differences in equivalent widths and the residual intensities with respect to the LTE profiles are indicated for the two lines. They are computed using Eq. (3). For better visibility of the differences between the profiles, we again show the 1D NLTE and 3D NLTE profiles separately in Fig. 3.