A motion compensation deinterlacer for producing a progressive scan signal from an interlaced signal comprising: (a) a motion compensation unit for deriving missing odd lines in an interlaced field at a current time from an odd field at a previous time (T-1) in the interlaced signal using motion vectors between the previous time and the current time; characterised by: (b) means for deriving a first confidence measure for the accuracy of the motion compensation unit using the known even lines of the interlaced field at the current time for which missing odd lines are to be derived and a previous motion compensated even field (MCT-1) at the previous time in the interlaced signal, said means being configured to compare the previous motion compensated even field with the interlaced field for which missing odd lines are to be derived by using those motion vectors representing the difference in position between pixels in the previous motion compensated even field and pixels in the interlaced field to correlate pixels in the previous motion compensated even field with the pixels in the interlaced field at positions shifted by said those motion vectors from the pixels in the previous motion compensated field; (c) means for deriving a second confidence measure for the accuracy of the motion compensation unit using known lines of an odd field in the interlaced signal at the previous time and an odd field in the interlaced signal at a next time (T+1) following the current time, said means being configured to compare the odd field at the previous time with the odd field at the next time by using said those motion vectors multiplied by 2 to correlate pixels in the odd field at the previous time with the pixels in the odd field at the next time at positions shifted by said those motion vectors multiplied by 2 from the pixels in the odd field at the previous time; and (d) means (14, 16) for selecting an output for display from at least the motion compensation unit and one other deinterlacing means in dependence on a combination of the derived confidence measures. (a) a motion compensation unit for deriving missing odd lines in an interlaced field at a current time from an odd field at a previous time (T-1) in the interlaced signal using motion vectors between the previous time and the current time; (b) means for deriving a first confidence measure for the accuracy of the motion compensation unit using the known even lines of the interlaced field at the current time for which missing odd lines are to be derived and a previous motion compensated even field (MCT-1) at the previous time in the interlaced signal, said means being configured to compare the previous motion compensated even field with the interlaced field for which missing odd lines are to be derived by using those motion vectors representing the difference in position between pixels in the previous motion compensated even field and pixels in the interlaced field to correlate pixels in the previous motion compensated even field with the pixels in the interlaced field at positions shifted by said those motion vectors from the pixels in the previous motion compensated field; (c) means for deriving a second confidence measure for the accuracy of the motion compensation unit using known lines of an odd field in the interlaced signal at the previous time and an odd field in the interlaced signal at a next time (T+1) following the current time, said means being configured to compare the odd field at the previous time with the odd field at the next time by using said those motion vectors multiplied by 2 to correlate pixels in the odd field at the previous time with the pixels in the odd field at the next time at positions shifted by said those motion vectors multiplied by 2 from the pixels in the odd field at the previous time; and (d) means (14, 16) for selecting an output for display from at least the motion compensation unit and one other deinterlacing means in dependence on a combination of the derived confidence measures.