Fig. 5.

(a) A TEM image, showing improved fibril neighborhood boundaries (red) for three representative fibrils. These boundaries are computed based on fitting an $N$-component Gaussian mixture model to all fibrillar pixel locations. (b) The same three neighborhood boundaries, plotted together with the probability density function of the resultant Gaussian mixture model. A region of interest surrounding one of the representative fibrils is enlarged for clarity. (c) The posterior membership probability field $P_i(u,v)$ for the Gaussian component (i.e., fibrillar pixel population) centered in the region of interest. The final neighborhood boundary, defined implicitly as the contour at which $P_i(u,v)=0.5$, represents that largest $P_i$-based region that is guaranteed not to overlap with any adjacent fibril neighborhoods, which are defined in the same way.