1. A charge-coupled device (CCD) Gray-to-binary code converter comprising, in combination: N input CCD channels for N charge signals G.sub.N-1. .. G.sub.0 indicative of an N digit Gray code, where G.sub.N-1 represents the digit of greatest significance and G.sub.0 the digit of least significance, each charge signal G.sub.j other than G.sub.0 comprising a charge packet which is substantially twice as large as the charge packet G.sub.j-1 representing the Gray code digit of next lower significance than G.sub.j ; means for deriving from the charge signal G.sub.N-1, a charge signal B.sub.N-1 indicative of the binary code digit of greatest significance; and N-1 means, each for adding to a different charge signal B.sub.j indicative of a binary code digit, a charge signal G.sub.j-1 indicative of the Gray code digit of next lower significance than said binary code digit, each such means for thereby obtaining a different sum charge packet S.sub.j-1 and for deriving from each said sum charge packet a charge signal B.sub.j-1 indicative of the binary code digit of j-1'th significance, where j is an integer having the values (N-1). .. 1.