Elongation/Compactness Shape Measurement Algorihtm

Goal: Measure how elongated versus compact (think rectangle versus square) a blob is.

Idea 1: Find the 2 principal axes of the blob data. Measure the maximum distance along axis 1 and along axis 2. Compactness = distance_minor_axis/distance_major_axis. If Compactness = 1 then Compact (square like...meaning very compact). If Compactness = small then Elongated (rectangle like ....not compact).