A general framework for multiresolution image fusion: from pixels to regions

This paper presents an overview on image fusion techniques using multiresolution decompositions. The aim is two-fold: ($i$) to reframe the multiresolution-based fusion methodology into a common formalism and, within this framework, ($ii$) to develop a new region-based approach which combines aspects of both object and pixel-level fusion. To this end, we first present a general framework which encompasses most of the existing multiresolution-based fusion schemes and provides freedom to create new ones. Then, we extend this framework to allow a region-based fusion approach. The basic idea is to make a multiresolution segmentation based on all different input images and to use this segmentation to guide the fusion process. Performance assessment is also addressed and future directions and open problems are discussed as well.