Twenty-Five Years of Pansharpening: A Critical Review and New Developments

Pansharpening is a branch of data fusion, more speci†cally of image fusion, which is receiving an ever-increasing attention from the remote sensing community. New-generation spaceborne imaging sensors operating in a variety of ground scales and spectral bands provide huge volumes of data having complementary spatial and spectral resolutions. Constraints on the signal-to-noise ratio (SNR) impose that the spatial resolution must be lower, if the desired spectral resolution is larger. Conversely, the highest spatial resolution is obtained whenever no spectral diversity is required. The trade-off of spectral and spatial resolution makes it desirable to perform a spatial resolution enhancement of the lower-resolution multispectral (MS) data or, equivalently, to increase the spectral resolution of the data set having a higher ground resolution, but a lower spectral resolution; as a limit case, constituted by a unique panchromatic image (Pan) bearing no spectral information.