Key points are not available for this paper at this time.
Radial and angular moments of images are presented and methods are shown for deriving moment functions that are invariant with respect to rotation, translation, reflection, and size changes without the aid of the theory of algebraic invariants. Hu's invariants are expressed in terms of these radial and angular moments and it is claimed that this facilitates visual inspection of invariance properties.
S. S. Reddi (1981) studied this question.