Hi there I'm thinking about using the rotation invarient moments by Hu/Flusser (http://en.wikipedia.org/wiki/Image_moment#Rotation_invariant_moments). I'm a physicist by trade, with exceptionally poor math..! I'm not comfortable with exactly what these invariants are. The wikipedia link describes the first as the moment of inertia of the image, while the final one is the skew, but doesn't describe any others. Is there an intuitive describtion of them, or are they just arbritary statistical measures of the image?