Motion estimation employing adaptive spatial update vectors

• US 20050243927A1
• Filed: 02/28/2005
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Grundmeyer, Michael, Hubrich, Ralf
• Granted Patent: US 7,920,627 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• CPC Class Codes: H04N 5/145 Movement estimation for video coding H04N19/51

Abstract

The present invention provides an improved method for motion estimation and in particular for a motion compensated interpolation. By taking the source of the video data into account, the size of update vectors to be employed for determining spatial prediction vectors is set in accordance with the detected source mode. By selecting an appropriate updata vector size, the accuracy of the predicted motion and consequently, the picture quality of motion compensated interpolated images can be increased considerably.

Claims

1. A method for determining a motion vector for a block of a current image in a sequence of video images, each video image being divided into a plurality of blocks, the method determining a motion vector for a current block by combing a previously determined motion vector and a predetermined update vector, further comprising the step of setting the size of said update vector depending on whether or not the image data of said current block stem from a motion picture type image:

2. A method according to claim 1, wherein a determination that image data stem from a motion picture type image is based on the detection of a motion picture to video data conversion pattern in the sequence of video images.

3. A method according to claim 2, wherein said conversion pattern being a 2:

2 or 3;

2 conversion pattern.

4. A method according to claim 1, wherein a determination that image data stem from a motion picture type image is determined on an image basis, in particular per field or frame.

5. A method according to claim 1, wherein a determination that image data stem from a motion picture type image is determined on a block basis.

6. A method according to claim 1, wherein the size of said update vector is set larger if said image data stem from motion picture film.

7. A method according to claim 6, wherein in case of motion picture film image data the size of said update vector being set between 1.5 and 2.5 as large, preferably twice as large, compared to the size of an update vector for no motion picture type image data.

8. A method according to claim 1, wherein said update vector being selected from a plurality of predetermined update vectors.

9. A method according to claim 1, further comprising the steps of:

selecting a motion vector for said current block from a plurality of candidate motion vectors including said motion vector estimated by combing a previously determined motion vector and a predetermined update vector, and

assigning said selected motion vector to said current block.

10. A method according to claim 9, wherein said selecting step comprising the steps of:

calculating an error value for each of the candidate motion vectors, and

selecting that motion vector having the smallest error value.

11. A method according to claim 9, wherein said candidate vectors include a plurality of combinations of a given previously determined motion vector with different update vectors from a plurality of predetermined update vectors.

12. A method according to claim 1, wherein said previously determined motion vector include at least one of the following motion vectors:

a zero motion vector pointing to the identical block position of the current block,

a motion vector determined for an adjacent block in the current image, and

a motion vector determined for a block in a previous image.

13. A method according to claim 9, wherein said candidate vectors further include at least one of the following motion vectors:

a zero motion vector pointing to the identical block position of the current block,

a motion vector determined for an adjacent block in the current image, and

a motion vector determined for a block in a previous image.

14. A method for encoding a sequence of video images including motion compensation employing a motion estimation method in accordance with claim 1.

15. A method for interpolating a sequence of video images including motion compensation employing a motion estimation method in accordance with claim 1.

16. A method for converting a field- or frame-rate of a video sequence by employing motion compensation in accordance with claim 15.

33. A method according to claim 2, wherein a determination that image data stem from a motion picture type image is determined on an image basis, in particular per field or frame.

34. A method according to claim 2, wherein a determination that image data stem from a motion picture type image is determined on a block basis.

17. A motion estimator for determining a motion vector for a block of a current image in a sequence of video images, each video image being divided into a plurality of blocks, the motion estimator determining a motion vector for a current block by combing a previously determined motion vector and a predetermined update vector, comprising:

a film mode detector determining whether or not the image data of said current block stem from a motion picture type image, and

adjusting means for setting the size of said update vector depending on whether or not the image data of said current block stem from a motion picture type image.

18. A motion estimator according to claim 17, wherein said film mode detector determining that image data stem from a motion picture type image based on the detection of a motion picture to video data conversion pattern in the sequence of video images.

19. A motion estimator according to claim 18, wherein said conversion pattern being a 2:

2 or 3;

2 conversion pattern.

20. A motion estimator according to claim 17, wherein said film mode detector determining that image data stem from a motion picture type image on an image basis, in particular per field or frame.

21. A motion estimator according to claim 17, wherein film mode detector determining that image data stem from a motion picture type image on a block basis.

22. A motion estimator according to claim 17, wherein said adjusting means setting the size of said update vector larger if said image data stem from motion picture film.

23. A motion estimator according to claim 22, wherein said adjusting means setting in case of motion picture film image data the size of said update vector being between 1.5 and 2.5 as large, preferably twice as large, compared to the size of an update vector for no motion picture type image data.

24. A motion estimator according to claim 17, wherein said adjusting means comprising a memory and selecting said update vector from a plurality of pre-stored update vectors.

25. A motion estimator according to claim 17, further comprising a selector for selecting a motion vector for said current block from a plurality of candidate motion vectors including said motion vector estimated by combining a previously determined motion vector and a predetermined update vector.

26. A motion estimator according to claim 25, wherein said selector comprising:

a processing unit for calculating an error value for each of the candidate motion vectors, and

a comparator for selecting that motion vector having the smallest error value.

27. A motion estimator according to claim 25, wherein said candidate vectors include a plurality of combinations of a given previously determined motion vector with different update vectors from a plurality of predetermined update vectors.

28. A motion estimator according to claim 17, wherein said previously determined motion vector include at least one of the following motion vectors:

a zero motion vector pointing to the identical block position of the current block,

a motion vector determined for an adjacent block in the current image, and

a motion vector determined for a block in a previous image.

29. A motion estimator according to claim 25, wherein said candidate vectors further include at least one of the following motion vectors:

a zero motion vector pointing to the identical block position of the current block,

a motion vector determined for an adjacent block in the current image, and

a motion vector determined for a block in a previous image.

30. An encoder for encoding a sequence of video images including motion compensation employing a motion estimator in accordance with claim 17.

31. An interpolator for interpolating a sequence of video images including motion compensation employing a motion estimator in accordance with claim 17.

32. A converter for converting a field- or frame-rate of a video sequence by employing motion compensation in accordance with claim 31.

35. A motion estimator according to claim 18, wherein said film mode detector determining that image data stem from a motion picture type image on an image basis, in particular per field or frame.

36. A motion estimator according to claim 18, wherein film mode detector determining that image data stem from a motion picture type image on a block basis.