Extinction maps of Galactic molecular clouds (left) and corresponding Δ-variance spectrum with errors (right). See Appendix C how the error using Poisson statistic was calculated. The gray scale range of extinction (A_V) is given in the wedge of each plot. The dashed lines indicate the pixel size (2′) and the size of the map. If the mapsize is larger than the x-axis scale (500 arcmin), its size is noted in the plot. The small-scale slope β and its error are given in each diagram, the fit range is indicated by two gray lines. The red curve for Perseus represents ¹³CO 1 → 0 data from the Bell Labs (see Table 1 and Bensch et al. 2001). The lower x-axis is labeled in arcmin, the upper one in parsec. All coordinates are in RA and Dec epoch2000.