Observed polarized emission at 353 GHz (in MJy sr^-1) of the Musca (left) and Taurus (right) clouds. The maps are at the resolution of 9.′6 (indicated by the white filled circles) for increased S/N. The black segments show the B_POS-field orientation (ψ+90°). The length of the pseudo-vectors is proportional to the polarization fraction. The blue contours show the total dust intensity at levels of 3 and 6 MJy sr^-1, at the resolution of 4.′8. The white boxes correspond to the area of the filaments and their backgrounds that is analysed in the rest of the paper.