Notes on Fabric's clustering and filtering.

Limited topology accepted as a cluster:
Highest, 2 nd highest and 3rd highest must form an L with the highest at the knee.
i.e. the second highest and the third highest can never lie on a diagonal with the highest.

This is the spirit behind his routine fLocate16PixCluster
In this routine the pixels of a 4 by 4 cluster are organized into the tLoc matrix where the first index of tLoc is the pixel number 0-15 and the second index is 0 or 1 designating the row or column of the pixel. The ordering of the 4 by 4 array to the 0-15 pixel index is shown in the following figure: