generic multiresolution fusion scheme
The basic idea of the generic multiresolution fusion scheme is motivated by the fact that the human visual system is primary sensitive to local contrast changes, i.e. edges.
Motivated from this insight, and in mind that both image pyramids and the wavelet transform result in an multiresolution edge representation, it is straightforward to build the fused image as a fused multiscale edge representation.
The fusion process is summarized in the following: In the first step the input images are decomposed into their multiscale edge representation, using either any image pyramid or any wavelet transform. The actual fusion process takes place in the difference resp. wavelet domain, where the fused multiscale representation is built by a pixel-by-pixel selection of the coefficients with maximum magnitude. Finally the fused image is computed by an application of the appropriate reconstruction scheme.
The figure above illustrates this generic fusion scheme.