A system (100) for processing remotely acquired imagery is provided. The system (100) includes a storage element for receiving imagery data defining a first image of a panchromatic image type using a sensor characterized by a panchromatic spectral response curve and 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. The first image has a first spatial resolution and a first spectral resolution. The second image has a second spatial resolution lower than the first spatial resolution and a second spectral resolution higher than that first spectral resolution. The system (100) also includes a processing element configured for deriving a radiation transfer model based on meta-data associated with one of the first and the second image and for determining a set of spectral weights for down-sampling the second image to the first spectral resolution based on the radiation transfer model and the panchromatic and the multi-spectral response curves.