Influence of spatial resolution on pan-sharpening results

Pan-sharpening techniques improve the spatial resolution of a Multispectral image (MS) by using a Panchromatic image (PAN) of the same scene contemporaneously acquired at higher resolution. Usually, a quantitative assessment of the resulting fused MS image cannot be directly performed because of the lack of a reference MS. Wald's protocol offers a possible solution: original Pan and MS are spatially degraded, the reducing factor being the ratio between their resolutions. Pan-sharpening is then performed between the reduced MS and PAN images. The quality of the fused products is then evaluated by comparing them with the original MS used as reference, by assuming the hypothesis that the performances of the pan-sharpening methods are independent from scale. The objective of this work is to propose a methodology to verify this hypothesis. For this aim, pan-sharpening performances when varying spatial resolution are investigated and a viable strategy to devise pansharpening performances at full scale is suggested.