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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.
INTRODUCTION
Improved 3DRS Algorithm Bi-directional Block Matching Multi-resolution Searching
EXPERIMENTAL RESULTS
CONCLUSION
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 pictureformat conversion frominterlaced to progressive pictures
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
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
INTRODUCTION
Improved 3DRS Algorithm BI-DIRECTIONAL BLOCK MATCHING MULTI-RESOLUTION SEARCHING
EXPERIMENTAL RESULTS
CONCLUSION
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
),( yx ddd
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 : dy mod 2 = 0
),( yx ddd
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.
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.
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=MV5?
falsetrue
n x n block
3DRS motion estimation
Candidate Set at Different Resolution(1/2) Original 3DRS construct a candidate set
spatial candidates, temporal candidates and update candidates
Candidate Set at Different Resolution(2/2) Improved 3DRS algorithm adopts different
compositions
16x16
8x8
4x4
increase horizontalsearch range
INTRODUCTION
Improved 3DRS Algorithm Bi-directional Block Matching Multi-resolution Searching
EXPERIMENTAL RESULTS
CONCLUSION
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. Paris2. Mobile & calendar
Subjective Visual Quality(2/2)1. Video sequence : paris
2. Video sequence : mobile & calender
a) Original 3DRS
b) improved 3DRS
a) Bi3DRS b) improved 3DRS
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]
Objective PSNR Performance(2/2)
the parameter C1 of AR error protection determines the ratio of temporal and spatial information
If parameter C1 ↑ spatial information ↑ => the impact of error propagation
↓ benefits from accurate motion estimation ↓
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.