1. An apparatus for measuring an image with many parts, the apparatus comprising: a one dimensional array of integrated circuit detectors, the detectors being spatially arranged with a pre-determined periodicity, each detector comprising: a photosensitive surface, measuring, at any one time during the measurement, a part of the image to produce a measured output, the detector having a non-uniform spatial sensitivity across the surface; the surface having at least one edge; and the sensitivity decreasing monotonically from the edge to an almost negligible sensitivity on a part of the surface; such that: at the end of the measurement, all parts of the image have been measured; and the image can be re-constructed by manipulating the measured outputs from the detectors with a signal processing scheme.