Downscaling in remote sensing

► This paper reviews methods for downscaling in remote sensing, that is, increasing the spatial resolution of images. ► Several methods for downscaling to (i) continua and (ii) categories from a coarse resolution continuous variable are reviewed. ► Area-to-point kriging, spatial optimisation techniques and multiple point geostatistics methods are considered. ► Several issues are discussed including the information content of training data, and the requirement for uncertainty estimates. ► The paper ends with a look towards the grand challenge of downscaling in the context of time-series image stacks.