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)

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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

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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