Motion compensation deinterlacer protection

1. A motion compensation deinterlacer for producing a progressive scan signal from an interlaced signal comprising:

(a) a motion compensation unit for deriving missing lines in an interlaced field from at least one other field in the interlaced signal;

(b) means for deriving a first confidence measure for the accuracy of the motion compensation unit using known lines of the field for which the missing lines are to be derived;

(c) means for deriving a second confidence measure for the accuracy of the motion compensation unit using known lines of at least two other fields;

(d) means for combining the first and second confidence measures; and

(e) means for selecting outputs for display from at least the motion compensation unit and one other deinterlacing means in dependence on the combined confidence measure.

2. A motion compensation deinterlacer according to claim 1 , including means for switching to a different deinterlacing means in dependence on the result of the combined confidence measure.

3. A motion compensation deinterlacer according to claim 2 , in which the different deinterlacing means is switched into use if one of the confidence measures falls below a predetermined value.

4. A motion compensation deinterlacer according to claim 2 , in which the means for switching to the different deinterlacing means comprises a blending unit which proportions the output of the motion compensation unit and one or more of the deinterlacing means to produce the outputs comprising a deinterlaced signal.

5. A motion compensation deinterlacer according to claim 1 , including means for determining a motion vector, and wherein the means for deriving a first confidence measure utilizes the motion vector.

6. A motion compensation deinterlacer according to claim 1 , including means for determining a motion vector, and wherein the means for deriving a second confidence measure utilizes the motion vector.

7. A motion compensation deinterlacer according to claim 1 , wherein the first confidence measure is based on how accurately the motion compensation means predicted pixels in a current field in comparison to actual pixel values.

8. A method for motion compensation deinterlacing for producing a progressive scan signal from an interlaced signal comprising the steps of:

(a) deriving missing lines in an interlaced field from at least one other field in the interlaced signal by motion compensation;

(b) deriving a first confidence measure for the accuracy of the motion compensation using known lines of the interlaced field for which missing lines are to be derived;

(c) deriving a second confidence measure for the accuracy of the motion compensation using known lines of at least two other fields;

(d) combining the first and second confidence measures to obtain a combined confidence measure; and

(e) selecting outputs for display from at least the motion compensation and one other deinterlacing means in dependence on the combined confidence measure.

9. A method according to claim 8 , including the step of switching to a different deinterlacing means in dependence on the result of the combined confidence measures.

10. A method according to claim 9 , including the step of switching to the different deinterlacing means when one of the confidence measures falls below a predetermined value.

11. A method according to claim 9 , in which the step of switching to the different deinterlacing means comprises the step of blending proportions of the motion compensation and one or more of the deinterlacing means to produce the outputs for an output deinterlaced signal.

12. A method according to claim 8 , including the step of determining a motion vector, and wherein the step of deriving a first confidence measure utilizes the motion vector.

13. A method according to claim 8 , including the step of determining a motion vector, and wherein the step of deriving a second confidence measure utilizes the motion vector.

14. A method according to claim 8 , wherein the first confidence measure is based on how accurately the motion compensation predicts pixels in a current field in comparison to actual pixel values.

15. A method for motion compensation deinterlacing for producing a progressive scan signal from an interlaced signal comprising the steps of:

determining safe outputs with a safe deinterlacer;

deriving motion compensation outputs;

deriving motion vectors;

deriving a first confidence measure from known lines of at least one of the fields and the motion vectors;

deriving a second confidence measure from known lines of at least two other ones of the fields and the motion vectors;

combining the first and second confidence measures to obtain a combined confidence measure; and

selecting outputs for the progressive scan signal from at least the motion compensation outputs and the safe outputs of the safe deinterlacer in dependence on the combined confidence measure.

16. A method according to claim 15 , wherein the motion vectors are derived from differences in position between pixels in a previous motion compensation field and another field.

17. A method according to claim 15 , wherein the motion vectors are derived from a number of the different fields.

18. A method according to claim 15 , wherein the step of selecting outputs comprises switching from the motion compensation outputs to the safe interlacer outputs when one of the confidence measures falls below a predetermined value.

19. A method according to claim 15 , wherein the step of selecting outputs further comprises the step of blending proportions of the motion compensation outputs and the safe outputs in dependence on the combined confidence measure.