Multispectral pansharpening based on pixel modulation: state of the art and new results

In this paper, the characteristics of pansharpening methods based on pixel modulation are investigated. It is found that all the modulation-based fusion methods significantly benefit, both visually and numerically, from setting a constraint also on the modulus of the detail vector, by means of a damping factor. Experiments on VHR MS+Pan data sets from different instruments highlight that such factor is always lower than one and depends on the instrument as well as on the landscape. Instead of a trial-and-error optimization, the value of the damping factor can be determined by minimizing some measurement of spatial distortion of fusion products. Sample values are reported for IKONOS and QuickBird instruments and different types of land cover.