1. An Improved 3DRS Algorithm for Video De-interlacing Songnan Li, Jianguo Du, Debin Zhao, Qian Huang, Wen Gao in IEEE Proc. Picture Coding Symposium (PCS), Beijing, China, Apr. 2006.

2.  INTRODUCTION  Improved 3DRS Algorithm  Bi-directional Block Matching  Multi-resolution Searching  EXPERIMENTAL RESULTS  CONCLUSION

3. Introduction  Traditional television systems adopted interlaced scan  As a tradeoff between frame rate and transmission bandwidth requirements  Some artifacts, such as flicker, serration  makes video coding less efficient and more complex  de-interlacing as a picture format conversion from interlaced to progressive pictures

4. De-interlacing methods(1/2)  Line doubling, line interpolation  frame rate identical to the field rate  used more frequently in high end consumer electronics  Weaving  forming a jagged edge

5. De-interlacing methods(2/2)  Directional dependent filtering  Adaptive adjust  Motion-Compensated (MC) interpolation  better results  massive requirements on computational resources and storage.  3D recursive searching (3DRS) algorithm has superiority at both true motion estimation and hardware complexity  forward block matching suffers from latent error propagation  fixed matching block size isn’t suitable for predicting different kinds of motion

6.  INTRODUCTION  Improved 3DRS Algorithm  BI-DIRECTIONAL BLOCK MATCHING  MULTI-RESOLUTION SEARCHING  EXPERIMENTAL RESULTS  CONCLUSION

7. Forward Block Matching for Original 3DRS  For each block B(x) at block position x of fn, the match error criterion is the Sum of Absolute Difference (SAD) which can be described as follow:  d : motion vector,  for x’ : y mod 2 = n mod 2  leads to the interpolation errors propagating into subsequent output frames

8. BI-DIRECTIONAL BLOCK MATCHING  assumption that the motion at forward and backward fields is consistent  For each block B(x) at position x of fn, the match error criterion for bi-directional block matching is as follows:  d : motion vector,, the restriction : d y mod 2 = 0

9. MULTI-RESOLUTION SEARCHING  Larger block size makes the motion estimation  less sensitive to noise  reduces the aperture problem  not suitable to small-area motion details  Adjust block size according to the video content.  First, at the lowest resolution, matching block sized 16x16  By split criterion, decide whether to go down to a higher resolution, four 8x8  smallest block size 4x4.

10. Split Criterion(1/2)  Observation:  A moving object from a long distance (at a low resolution)  It may contain many types of motion.  Pay attention to a part of it (at a high resolution)  You will get a series of similar motions.

11. Split Criterion(2/2)  formalized as follow:  Function f returns true or false  depending on the similarity of 9 MVs get MV split to four (n/2)x(n/2) block higher resolution At least 5MVs=MV 5 ? false true n x n block 3DRS motion estimation

12. Candidate Set at Different Resolution(1/2)  Original 3DRS construct a candidate set  spatial candidates, temporal candidates and update candidates

13. Candidate Set at Different Resolution(2/2)  Improved 3DRS algorithm adopts different compositions 16x16 8x8 4x4 increase horizontal search range increase horizontal search range

14.  INTRODUCTION  Improved 3DRS Algorithm  Bi-directional Block Matching  Multi-resolution Searching  EXPERIMENTAL RESULTS  CONCLUSION

15. Subjective Visual Quality(1/2)  Step1: extract interlaced videos from progressive sequences by dropping one field in each frame  Step2 : de-interlace the generated videos using  original 3DRS algorithm  improved 3DRS algorithm, respectively.  Video sequence: 1. Paris 2. Mobile & calendar

16. Subjective Visual Quality(2/2) 1. Video sequence : paris 2. Video sequence : mobile & calender a) Original 3DRSb) improved 3DRS a) Bi3DRSb) improved 3DRS

17. Objective PSNR Performance(1/2)  7 CIF progressive sequences and 2 HD progressive sequences are selected.  test 3 de-interlacing algorithms:  original 3DRS, Bi3DRS and improved 3DRS algorithm.  each of them is followed by the AR error protection[11]

18. Objective PSNR Performance(2/2)  the parameter C 1 of AR error protection determines the ratio of temporal and spatial information  If parameter C 1 ↑  spatial information ↑ => the impact of error propagation ↓  benefits from accurate motion estimation ↓

19. CONCLUSION  3DRS algorithm is an efficient motion estimation method for the video de-interlacing process  Improve 3DRS algorithm to overcome some deficiencies  bi-directional block matching  to eliminate error propagation  multi-resolution searching  to adjust matching block size according to the video content.  Experiments show that better subjective and objective results than the original 3DRS algorithm on most tested sequences.