1. A method for operating a data processing system to generate a second image from a first image, said first image comprising a two dimensional array of pixel values, each of said pixel values corresponding to the light intensity in one of a plurality of spectral bands at a location in said first image, said method comprising the steps of: separating said pixels of said first image into a plurality of input image planes, each input image plane having an identical number of pixels within a normalized horizontal and vertical sampling interval as the other input image planes, and all pixels in a given input image plane having the same spectral band as the other pixels in that input image plane; representing said first image as a set of super input pixels, each of said super input pixels being a vector of dimension P, where P is the number of said input image planes, each component of that vector being an input pixel from a corresponding input image plane; defining a set of output image planes, each pixel in a given output image plane representing the intensity of said second image in one of a plurality of spectral bands at a corresponding point in said second image; representing said second image as a set of super output pixels, each super output pixel being a vector of dimension Q, where Q is the number of said output image planes, each component of that vector being a pixel from a corresponding output image plane; and applying a linear transformation to a vector derived from said super input pixels to obtain a vector comprising at least one of said super output pixels.