Upper parts of both panels: performance of the Xpol (blue points, see Sect. 3.1.1) and Xpure (red squares, see Sect. 3.1.2) algorithms on the power spectrum for Gaussian simulations of the dust polarization in the LR24 region (top panel, defined in Sect. 3.3.1) and in M_B2 (bottom panel, defined in Sect. 6.1). The signal input power spectrum is shown as a dashed grey line and its associated sample variance as a light grey shaded area. Lower parts of both panels: relative discrepancy with respect to the input power spectrum.