Neighbourhood Potential
A Neighbourhood Potential is the combination of a raster with a kernel.
r := Potential(d,K) implies that $r_{ij} = \sum\limits_{kl} d_{i-k, j-l} \times K_{kl}$
This is AKA convolution. See also the potential function and the potential-with-kernel.
If we ignore the terms that are cut off at the borders, then $\sum\limits_{ij} R = \sum\limits_{ij} d \times \sum\limits_{kl} K$. The values unit of R is defined as the product of the values units of d and K.
Note the similarity of this operation with the multiplication of two polynomials in two unknowns, take:
$d(x,y) := \sum\limits_{ij} d_{ij} \times x^i \times y^j$
$K(x,y) := \sum\limits_{kl} K_{kl} \times x^k \times y^l$
$R(x,y) := \sum\limits_{ij} R_{ij} \times x^i \times y^j$
It follows that
R(x,y) = d(x,y) * K(x,y) if we ignore the terms that are cut off at the borders.