Fig. 5. Cumulative relative distributions of the number of pixels of each habitat type, as classified by the maximum likelihood (ML) classification in 14,030 squares measuring 3 x 3 pixels sampled randomly among all peatlands (black squares) and in squares measuring 3 x 3 pixels in which the bottom-left pixel corresponded to one of the 626 validation locations (black circles). The area between the two curves is proportional to the improvement of the classification over a random distribution of habitat classes. Because both classification procedures gave similar results, we present the frequency distribution curves for the ML procedure only. Habitat codes are defined in Table 1.