Color-crossing error suppression system and method for decoded composite video signals

1. A method of suppressing color-crossing error in decoded video signals representing a plurality of fields, the method comprising:

determining a count value with a color-crossing error suppression unit based on chrominance values;

using a first suppression technique with the color-crossing error suppression unit at a pixel location for a first subset of fields exhibiting color-crossing error at the pixel location, when the count value is greater than an initial threshold;

using a second suppression technique with the color crossing error suppression unit at the pixel location for a second subset of fields exhibiting color-crossing error at the pixel location, when the count value is greater than a final threshold, wherein the second subset of fields follows the first subset of fields in the video signal.

2. The method of claim 1 , wherein the first suppression technique is an averaging technique and the second suppression technique is an iterative technique.

3. The method of claim 1 , wherein the first suppression technique is an iterative technique using a large weighting factor and the second suppression technique is an iterative technique with a small weighting factor.

4. The method of claim 1 , wherein the first suppression technique further comprises:

calculating an updated U chrominance value for a current pixel of a current field by averaging U chrominance values from a set of corresponding pixels; and

calculating an updated V chrominance value for the current pixel by averaging V chrominance values from the set of corresponding pixels.

5. The method of claim 4 , wherein the set of corresponding pixels includes the current pixel and a corresponding pixel from each of three fields of the same field type as the current field following the current field.

6. The method of claim 4 , wherein the decoded video signals are PAL video signals, the current field is field F(i), and the set of corresponding pixels includes the current pixel and the corresponding pixel from field F(i+4).

7. The method of claim 4 , wherein the decoded video signals are NTSC video signals, the current field is field F(i), and the set of corresponding pixels includes the current pixel and the corresponding pixel from field F(i+2).

8. The method of claim 1 , wherein the second suppression technique further comprises:

calculating an updated U chrominance for a current pixel, wherein the updated U chrominance value is equal to a weighted average of a U chrominance value of the current pixel with a U chrominance value of a corresponding pixel from a previous field; and

calculating an updated V chrominance for the current pixel, wherein the updated V chrominance value is equal to a weighted average of a V chrominance value of the current pixel with a V chrominance value of the corresponding pixel from the previous field.

9. The method of claim 8 , wherein the decoded video signals are NTSC video signals, the current field is field F(i), and the previous field is field E′(i−2).

10. The method of claim 8 , wherein the decoded video signals are PAL video signals, the current field is field F(i), and the previous field is field F(i−4).

11. The method of claim 8 , wherein the decoded video signals are PAL video signals, the current field is field F(i), and the previous field is field F(i−2).

12. A color-crossing error suppression system, for processing a decoded video signals representing a plurality of fields, comprising:

means for determining a count value based on chrominance values;

means for using a first suppression technique at a pixel location for a first subset of fields exhibiting color-crossing error at the pixel location, when the count value is greater than an initial threshold;

means for using a second suppression technique at the pixel location for a second subset of fields exhibiting color-crossing error at the pixel location, when the count value is greater than a final threshold, wherein the second subset of fields follows the first subset of fields in the video signal.

13. The color-crossing error suppression system of claim 12 , wherein the first suppression technique is an averaging technique and the second suppression technique is an iterative technique.

14. The color-crossing error suppression system of claim 12 , wherein the first suppression technique is an iterative technique using a large weighting factor and the second suppression technique is an iterative technique with a small weighting factor.

15. The color-crossing error suppression system of claim 12 , wherein the first suppression technique further comprises:

means for calculating an updated U chrominance value for a current pixel of a current field by averaging U chrominance values from a set of corresponding pixels; and

means for calculating an updated V chrominance value for the current pixel by averaging V chrominance values from the set of corresponding pixels.

16. The color-crossing error suppression system of claim 15 , wherein the set of corresponding pixels includes the current pixel and a corresponding pixel from each of three fields of the same field type as the current field following the current field.

17. The color-crossing error suppression system of claim 15 , wherein the decoded video signals are PAL video signals, the current field is field F(i), and the set of corresponding pixels includes the current pixel and the corresponding pixel from field F′(i+4).

18. The color-crossing error suppression system of claim 15 , wherein the decoded video signals are NTSC video signals, the current field is field E(i), and the set of corresponding pixels includes the current pixel and the corresponding pixel from field F(i+2).

19. The color-crossing error suppression system of claim 12 , wherein the second suppression technique further comprises:

means for calculating an updated U chrominance for a current pixel, wherein the updated U chrominance value is equal to a weighted average of a U chrominance value of the current pixel with a U chrominance value of a corresponding pixel from a previous field; and

means for calculating an updated V chrominance for the current pixel, wherein the updated V chrominance value is equal to a weighted average of a V chrominance value of the current pixel with a V chrominance value of the corresponding pixel from the previous field.

20. The color-crossing error suppression system of claim 19 , wherein the decoded video signals are NTSC video signals, the current field is field F(i), and the previous field is field F(i−2).

21. The color-crossing error suppression system of claim 19 , wherein the decoded video signals are PAL video signals, the current field is field F′(i), and the previous field is field F(i−4).

22. The color-crossing error suppression system of claim 19 , wherein the decoded video signals are PAL video signals, the current field is field F(i), and the previous field is field F(i−2).