High Frame Rate Up Conversion

Ana Bertran

Problem Statement

Original Frame

(30 fps)

Dwnsmpld Frame

(5 fps)

Recovered Frame

(30 fps)

S & H

LI

MCLI

MCwA

Hypothesis: if we have acceleration MCwA should provide better results

X=a+b*sin(*t), vx=b**cos(*t), ax=-(b*2*sin(*t)

MotivationUses of frame rate up conversion: Converting between standards (PAL to NTSC). Using MCwA less critical

since frame rates not too far from each other. Low bit rate compression for video-confrncng, video-phone and video

games. MCwA becomes more critical (from 10 fps to 30 fps)

Problems with traditional methods: S&H motion looks jerky, not smooth, very choppy Linear interpolation without motion: image looks blurry where motion has

occurred, we will see ghosts due to avg. btwn. frames.

Motivation

Original

Linear Interpolation Sample & Hold

MCLI vs. MCwA

ME Catalog Occsns

LMC

AMC

ME

For forward and backward MVs

Overlapping BM

16x16 blcks, move by 8

Finer MV Selection

• Top Left block use its MV• 1st row blocks min SAD(L, current or next frame)• 1st colmn blocks min SAD(T, current or next frame)• others min SAD(T, L, current or next frame)

½ pixel MV zoom in

Take out illegal MVs

Cataloging Occlusions

1 2 3 4

For covered pixels we need to use frame 2 as the predicted image, one whose blocks we serch for.

For uncovered pixels we need to use frame 3 as the predicted image, one whose blocks we serch for.

Need to track block from 3 to 2

Criteria: compare SADs dependingwhich one minimum classify.

Cataloging Occlusions Results

blue=uncovred=covGreen=no occsn

blue=uncovred=no occsn

LMC

3 cases

No occlusions

Uncovered pixels

Covered pixels

No occlusions Occlusions

For each block along motion trajectory:MVx_est=w*MVx_3_2

MVy_est=w*MVy_3_2

Motion will be non-integer: interpolate

Assumed motion in xDepending on +ve/-ve x mtn, unvov/cov:

3 2

AMCTo solve distancex=vx*t+0.5*ax*t2 you need two MVs but you can get moreaccurate motion trajectories by solving a LMS problem on 3 MVs.

For each MV between two frames take the previous and next MVs to estimatethe trajectory.

Need to solve:

Frame rate up conversion a difficult problemNeed to use true motion vector fields but block matching does

poorly with this, specially across object boundaries and if the moving object is too small. Can´t cope with discontinuities in the velocity plane.

Some motion can fall in between pixels

Dealing with occlusions

Motion can change dramatically between frames and we won´t realize it. (Critical vels)

Not to talk about scene changes! – we no longer will have enough MVs to track motion trajectory.

Results/Demo

Will have the demo in the website by the end of

the week.

For now you can see the demo for the other types of FR up-conversion

Current temporary results

Future Work

Need better MV estimation of the true MVs

Implement ½ pixel resoltn or Use hierarchical block matching to

find true motion MVs or Object based interpretation of the

video to smooth out MVs Use 3D Recursive Search Block

Matching

Solve occlusion problem for both x and y movement

References

Using Motion-Compensated Frame-Rate Conversion for the Correction of 3:2 Pulldown Artifacts in lman, Video Sequences, Kevin Hilman, Hyuon Wook Park, and Yongmin Kim

True-Motion Estimation with 3-D Recursive Search Block MatchingGerard de Haan, Paul W.A.C. Biezen, Henk Huijgen and Olukayode A. Ojo

Digital Video Standards Conversion in the presence of accelerated motionAmdrew J. Patti, M. Ibrahim Sezan and M.Murat Tekalp

Framee Rate Up- Conversion using transmitted true motion vectorsYen-Kuang Chen, Anthony Vetro, Huifang Sun, and S.Y. Kung