A family of generalised complex Hadamard transforms using the concept of po
larity is introduced. Forward and inverse transformation kernels and method
s of recursive generation of transform matrices using Kronecker products of
elementary matrices are shown. Mutual relationships among transform matric
es and spectra for arbitrary polarities are presented. Efficient ways of ca
lculating spectra for logic functions through decision diagrams are also sh
own. The half-spectrum property is used to reduce further the computational
requirements for both fast transforms and decision diagram based calculati
ons.