678326.fig.001a
(a)
678326.fig.001b
(b)
678326.fig.001c
(c)
678326.fig.001d
(d)
678326.fig.001e
(e)
Figure 1: Map (a) with its erosion (b), dilation (c), opening (d), and closing (e) with a disk of radius 3 pixels. Method of the plain histogram.