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High-Quality Spatial High-Quality Spatial InterpolationInterpolation
of Interlaced Videoof Interlaced Video
Alexey LukinAlexey Lukin
Moscow State University, 2008
22/13/13
Interlaced-scan videoInterlaced-scan video
Invented in 1930-iesInvented in 1930-ies Video frame is separated into 2 fields Video frame is separated into 2 fields
(even and odd raster lines)(even and odd raster lines) Improvement of motion smoothness w/o Improvement of motion smoothness w/o
increase of signal bandwidthincrease of signal bandwidth
33/13/13
Interlaced-scan videoInterlaced-scan video
Invented in 1930-iesInvented in 1930-ies Video frame is separated into 2 fields Video frame is separated into 2 fields
(even and odd raster lines)(even and odd raster lines) Improvement of motion smoothness w/o Improvement of motion smoothness w/o
increase of signal bandwidthincrease of signal bandwidth
44/13/13
DeinterlacingDeinterlacing
Computer displays are progressive-scan Computer displays are progressive-scan → deinterlacing is needed→ deinterlacing is needed
Simplest deinterlacing methods:Simplest deinterlacing methods:► “Bob” (line averaging) ► “Weave” (field insertion)
spati
al in
terp
ola
tion
tem
pora
l in
terp
ola
tion
55/13/13
DeinterlacingDeinterlacing
Advanced deinterlacing methods:Advanced deinterlacing methods:
►Motion-adaptive: use “Bob” method in Motion-adaptive: use “Bob” method in motion areas, use “Weave” method in still motion areas, use “Weave” method in still areasareas
►Motion-compensated: use motion Motion-compensated: use motion compensation to temporally align fields in compensation to temporally align fields in motion-adaptive methodmotion-adaptive method
66/13/13
Spatial interpolationSpatial interpolation
High-quality spatial interpolationHigh-quality spatial interpolation Simple approaches:Simple approaches:►Line averaging, cubic interpolationLine averaging, cubic interpolation►ELA (Edge-Directed Line Averaging)ELA (Edge-Directed Line Averaging)
Known field pixels
Pixel to be interpolated
77/13/13
Spatial interpolationSpatial interpolation
Problem with ELA: uncertain Problem with ELA: uncertain interpolation direction in presence of interpolation direction in presence of thin linesthin lines
?
Line averaging ELA (5 directions)
88/13/13
Proposed methodProposed method
Aperture extensionAperture extension►Allows interpolating near-horizontal edgesAllows interpolating near-horizontal edges
Spatial averaging of derivativesSpatial averaging of derivatives►Improves the robustness of edge sensingImproves the robustness of edge sensing
d = -8 d = 8
)||()( dbarounddR
99/13/13
Proposed methodProposed method
Mixing of interpolation directionsMixing of interpolation directions►Tolerates inaccurate detectionTolerates inaccurate detection
of edge directionof edge direction
Expectation MaximizationExpectation Maximization
algorithmalgorithm►Re-estimation of derivativesRe-estimation of derivatives
from the interpolated imagefrom the interpolated image
Calculatedirectional derivatives
Smoothdirectional derivatives
Calculate weightsand interpolate pixels
Initial interpolation(line averaging)
2 iterations done?
Video frame
Yes
No
Finished
8
},01.0max{
d
dd D
MW
1010/13/13
ResultsResults
lthouse houses lthouse2 portrait boat leaves lena moto MEAN
-5.5
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
PS
NR
imp
rove
men
t, dB
Test image
Line averaging ELA 3 ELA 5 EDDI Proposed method
PSNR evaluation
1111/13/13
ResultsResultsVisual quality
Line averaging ELA (5-directional) EEDI2 method (free software)
EDDI method (G. de Haan) MSU algorithm, 2003 Proposed method
1212/13/13
ResultsResultsVisual quality
ELA (5-directional) Proposed method Proposed method+
motion compensation
1313/13/13
ConclusionConclusion
The developed method has:The developed method has:
►High visual quality and good PSNR figuresHigh visual quality and good PSNR figures
►Simple structureSimple structure
►High computational complexity High computational complexity (optimizations (optimizations possible)possible)
1414/13/13
Your questionsYour questions
??Thank youThank you
http://imaging.cs.msu.ru/~lukin/deinterlacing.html