Results of TM using four different templates. The analysed data are the 250 μm surface brightness map of LDN 1642 in Fig. B.2. The four templates (named on the left side of the figure) are depicted in Fig. B.1. Each pair of frames shows the S and θ maps of one extraction. On each row, the first two frames correspond to F₁ = 1′ and the last two frames to F₁ = 2′. The colour scale of S maps is the same as for the position angles, with a different but a fixed numerical scale. Pixels with S below the 80% percentile value have been masked.