Image fusion performance metric based on mutual information and entropy driven quadtree decomposition

The mutual information (MI) measure has become a popular metric to assess image fusion performance. However, despite its publicity, it provides a questionable result that consistently favours additive fusion (averaging) over multi-scale decomposition (MSD) fusion algorithms. Presented is a localised variation of MI to assess image fusion performance while preserving the importance of local structural similarity. The presented metric has been validated with extensive tests on popular image fusion test cases.