Averaged signal-to-noise ratio (P^∗/σ) as a function of the true ratio P_T/σ after applying: the bias suppression method; the Wardle & Kronberg method (using C = 1.2); our new method; and without any bias correction. To show the improvement of the bias suppression with our new method, we created a 100 × 100 pixel Û map and map that contained only Gaussian noise. We added a constant positive value A to the entire Û map and a negative value −A to the map. The values vary between 0 < | A | < 3σ. For each A we calculated the corresponding P^∗ as the average value over the entire map for all methods given in the plot.