Stokes parameters Q (top left), U (top right), V (middle left), and I (middle right); degree of polarization p (bottom left), and polarization angle φ (bottom right). Stokes parameters are normalized with respect to the total value of I integrated over the entire torus and including the contribution from the central source. The degree of polarization is given in fractions. The polarization angle is computed with respect to the y-axis. For better visualization, φ is also shown as a vector with sizes corresponding to p.