READING INFORMATION STORED IN MULTIPLE FRAME FORMAT

摘要

A method of reading information stored in a medium in one or more channels (14) of successive record frames (15) each containing a plurality of discrete record entries (15a) indicative of values from a limited set of possible values. Each frame is observed in turn with a substantially known array (16) of detector elements (18) such that each record entry influences the state and/or output of at least one detector element, whereby to produce a first set of observed values (Fig 4B) for each frame represented by the states and/or outputs of the detector elements. The limitations on the range of the aforesaid possible values are then utilised to derive from the observed values for each frame a set of modified values indicating record entries of the frame. One or more marker patterns are identified among the modified values, and such marker pattern(s) then utilised to derive from the modified values an accurate representation (Fig 4C) of the record entries of the frame. The derivations are effective to correct for any misregistration between the record entries and the detector elements.