1. A method of correcting a distorted input image comprising: determining a local region of an image to be displayed and dividing said region into an array of tiles, each tile having a boundary defined by a plurality of nodes, each node having a set of coordinates within said image space; for each tile of the local region, transforming said node coordinates according to a first local transformation to take into account a local distortion of said input image in said local region; determining a second global transformation mapping coordinates for a global array of nodes to take into account a global distortion of said input image; for each node of each tile of the local region: i) determining nodes of the global array immediately surrounding the node; ii) interpolating the transformation of the surrounding global node coordinates to transform the at least locally transformed coordinates of the node according to the global transformation; for each tile of the local region: i) reading a non-rectangular portion of said distorted input image corresponding to the locally and globally transformed node coordinates of said tile; ii) correcting the distortion of said non-rectangular portion of said distorted input image to provide a tile of a corrected output image; and storing said corrected tiles for said output image.