1. A method for iterative derivation of a master image from a plurality of sampled images of non-identical, at least partially overlapping, regions of a scene, the master image having an output resolution greater than a maximum resolution of the sampled images, the method comprising: (a) for each sampled image, defining: (i) a transformation operator F mapping positions within the master image to corresponding positions in the sampled image, (ii) a distortion operator H simulating a distortion associated with an imaging sensor from which the sampled image was generated, and (iii) a sampling operator D for reducing an image from the output resolution to the resolution of the sampled image; (b) for each sampled image, applying said transformation operator, said distortion operator and said sampling operator to a current master image hypothesis so as to generate a predicted image, and calculating a difference image having pixel values corresponding to the difference in corresponding pixel values between the sampled image and the predicted image; (c) performing back-projection of each of said difference images to generate a correction image for the current master image hypothesis; and (d) employing said correction images to perform a correction to the current master image hypothesis to generate a new master image hypothesis, wherein said back projection includes employing an operator H bp corresponding to a pseudo-inverse of, distortion operator H, wherein H bp approximates to an inverse of H at spatial frequencies below a given value and approaches zero at spatial frequencies above said given value, and wherein H bp is chosen to substantially satisfy the condition: 
 H bp ×D t ×D×H=I wherein: I is the unit operator for an image of the output resolution; D is a sampling operator for reducing an image from the output resolution to the resolution of an input image; and D t is an inflation operator for expanding an image from the resolution of the input image to the output resolution.