Tensorial manifest invariant index notation is the most common notation used to express invariants. is the result of applying filter to an image, hence is a second order tensor. A polynomial invariant of the L terms can be constructed by expanding the Manifest Invariant notation using Einstein summation [ 7 ]. For example the second order invariant expands as follows in two dimensions:
As well as the L tensors, represents a constant tensor known as Epsilon or the Levi-Civita tensor. In D dimensions Epsilon has D indices and is defined as follows:
Kevin Walker