Optimal Motion Vector Search Algorithm
6th Team
20032026 Kim, Hyun-Seok
20032072 Jang, Sun-Yean
20032077 Jung, Yu-Chul
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Overview ☆
- Terminology
- Block Matching
- Motion Vector Search Algorithms
- Considering Points
- Our Suggestion
- Implementation Outline
- References
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Terminology ☆
• Reference Frame : Frame in past (or future) used to predict
in current frame
• Current Frame: Frame which is being analyzed to derive
motion vectors
• Motion vector : The displacement of the closest matching block
in reference frame for a block in current frame
• Motion Estimator : Process of determining the values of motion
vectors for each frame
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Block Matching ☆
-to find the “best” block from an earlier frame to construct
an area of the current frame
d  (d x , d y )
MAD  Distortion( Bk (n), d ) 

( x , y )Bk ( n )
| U k ( x, y)  U r ( x  d x , y  d y ) |
-Goal is to find a vector where MAD(Mean Absolute Difference)
is minimum.
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Previous Approaches
I.
☆
Full Search
- Every possible block in the previous frame is examined
- Of all the blocks examined, the lowest MAE produced is chosen, and the
motion vector from that block’s position to the current block’s position is
generated.
- Problems : The most precise matching, but the most demanding in terms of
computational complexity. (2w+1)^2 times
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Previous Approaches(cont’) ☆
II. Conjugate Direction Search
- based on the assumption that the energy of the prediction error is
monotonically decreasing towards the optimum motion vector in the search
range.
1) first, search along the horizontal row of blocks in the previous frame
The MAD is computed between each of these blocks
2) Then, extent the search in the vertical direction, searching the column of
blocks in the previous frame which have the same x-coordinate as the
best matching block founded in step 1)
Comparing with the full search,
complexity is reduced noticeably  3+2w
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Previous Approaches (cont’) ☆
III. Modified Logarithmic Search
- efficient and fast  2+7log(w)
- unable to search all of the locations at the boundaries of the search window,
thus, it doesn’t always result in the optimum notion vector within the
search window. However, its performance is very good for small
displacements.
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Considering Points ☆
-
Full search is simple and correct, but computational
burden.
-
Other approaches are apt to get trapped in local minima,
resulting in a significant loss in estimation accuracy, and
compression performance in video coding, as compared to
the Full search
☆ What is needed?
-
Novel motion vector prediction technique
-
A highly localized search pattern
-
A computational constraint explicitly incorporated into
the cost measure
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Our Suggestion ☆
Concepts
1. Employ a representative value based on bit information
:To maximize the correctness in potential motion changes
2. Use memory hash table
: To reduce computational time
3. Use Nearest Neighbor hood Algorithm
:To reduce the possibility of getting
trapped in local minima
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ Implementation Outline ☆
-최근 색채의 중요성이 강조->
소비자의 개성과 취향을 고려하고 트랜드를 쫓아 과감한 형태의
Reference
다양한 색채로
디자인된 제품들이 많이 출시됨
Frame
Current Frame
-최근(작년) 출시된 스피커 비오랩(Beolab) ;
소비자들의 주문을 통해 색상 선택하는 시스템 실시
->소비자들로 하여금 색상을 선택할 수 있는 기회를 주는 것이다.
Computing
time1 선도한다.”
Alg않는다.
1
Similarity 1
-“트랜드를 따르지
우리는
스타일을
-> B&O사의 BeoLab의 생산방식에 새롭게 채택한 방식은
Computing time2
Alg 2
Similarity 2
다른 제품사들과는 더 적극적인 색채전략의 필요성을 고려한 방식
장엄하고 권위적인
아닌 안락함과
제공해주는
time3 편안함을
Alg 3 사치가Computing
Similarity
3
보다 대중적인 오디오시스템의 이미지 마케팅을 위해 채택한 방식.
이것은 시장확대에
수행.
time4
Alg 4큰 역할 Computing
Similarity 4
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL
☆ References ☆
1.
Correlation Based Search Algorithms for Motion Estimation
Mohamed Alkanhal, Deepak Turgaga and Tsuhan Chen – E/CE of CMU, USA
(Picture Coding Symposium Portland, OR, April 21~23, 1999)
2.
An Efficient Computation-Constrained Block-Based Motion Estimation Algorithm
for Low Bit Rate Video Coding
Michael Gallant and Faouzi Kossentini – E/CE of UBC, Canada
3.
Motion Vector Refinement for High-Performance Transcoding
Jeongnam Youn, Ming-Ting Sun, Fellow, IEEE, and Chia-Wen Lin
IEEE Transaction on Multimedia, Vol. 1, No. 1, March 1999
4.
Computation constrained fast-search motion estimation algorithm for TMN 7. In
Q15-A-45, ITU-T Q15/SG16, Portland, Oregon, June 1997
5.
http://www.dcs.warwick.ac.uk/research/mcg/bmmc/index.html
Digital Media Lab
Concrete Mathematics
KIM, HYUNSEOK / JANG, SUNYEAN / JUNG , YUCHUL