1. A method for processing remotely acquired imagery, comprising: obtaining, by at least one electronic circuit, imagery data defining a first image of a panchromatic image type using a sensor characterized by a panchromatic spectral response curve, said first image having a first spatial resolution and a first spectral resolution; obtaining, by the electronic circuit, imagery data defining a second image of a multi-spectral image type using at least one other sensor characterized by a plurality of multi-spectral response curves associated with a plurality of optical bands, said second image having a second spatial resolution lower than said first spatial resolution and a second spectral resolution higher than that first spectral resolution; deriving, by the electronic circuit, a radiation transfer model based on meta-data associated with at least one of said first and said second image; and determining, by the electronic circuit, a set of spectral weights for down-sampling said second image to said first spectral resolution based on said radiation transfer model and said panchromatic and said multi-spectral response curves.