A motion compensation deinterlacer for producing a progressive scan signal from an interlaced signal includes a motion compensation unit that derives missing lines in an interlaced field from at least one other field in the interlaced signal. The deinterlacer includes a device that derives a first confidence measure for the accuracy of the motion compensation unit using known lines of the field for which missing lines are to be derived. Another device derives a second confidence measure for the accuracy of the motion compensation unit using known lines of at least two other fields. The first and second confidence measures are combined. An output unit selects outputs for display from at least the motion compensation unit and one other deinterlacing device in dependence on the combined confidence measures.