new requirement of subjective video quality assessment methodologies for 3dtv wei chen(*) 1,2,...

New requirement of subjective video quality assessment methodologies for 3DTV

Wei Chen(*)1,2, Jérôme Fournier1, Marcus Barkowsky2, Patrick Le Callet2

1Orange labs, France télécom R&D2IRCCyN IVC Team, Ecole Polytechnique de Nantes

Orange labs R&D - IRCCyN IVC Team 1VPQM 2010

Motivation

• A high quality 3DTV broadcast service is becoming more and more realistic.

VPQM 2010 Orange labs R&D - IRCCyN IVC Team 2

End-user

Visual quality

ExcellentBad

Good

Fair

poor

Naturalness

Presence

3D perception

visual experience

Visual Comfort

eye strain

etc.

Headache

etc.

Network

Mobile (WiMax, 3GLTE)

xDSL, FTTx, …

Codec

Proprietary

Standardised

New generations

MPEG-C, MVC, LDV

Terminal

Anaglyph system

Active Shutter Glass Glasses

system

Passive (Ploarised) Glasses system

Autostereoscopic system

Production

AV acquisition

Post-production

2D/3D conversion

Multiview interpolation

View synthesis from 3D representations

Mixed reality (augmented reality)

3D/3D conversion …

2D+z

Multi-viewOthers

Coming generations

DES

• Subjective video quality assessment– Evaluation the human perception– Optimize 3DTV systems– Ease the specification process for end to end

application– A solid reference for objective quality metrics.– Comparison of the results from different

laboratories

• However, 2D subjective video quality assessment can not fulfill this requirements.


Content

• 1.Novel condition and requirements(selected) of 3DTV regarding subjective quality assessment.

• 2.Depth rendering of 3DTV– A new notion: depth rendering ability– Comparison of different 3D displays

• 3.Conclusion


General Viewing ConditionsLuminance and contrast ratio

• Screen luminance ≠ Perceived luminance

• crosstalk affects contrast ratio


-80%

-60%

General Viewing Conditions Monitor resolution

• Recommendation of minimum values for spatial per view resolution


1080i/p960x1080

L

R Line Interlaced

960x1080

1920x540L R

Column Interlaced

1920x540

640x360 L R

Multi-views

640x360

L

R

Full resolution

1920x1080

1920x1080

General Viewing Conditions Background and room illumination

• Minimum distance between display and background necessary

• Technology of room illumination critical


?

Wall

TVTV

Neon illumination

General Viewing Conditions Viewing distance

• Adding depth perception factor into Preferred Viewing Distance– Depth of Focus depends on viewing distance

– Depth rendering also relates viewing distance

• Preferred Viewing Distance sometimes fixed by display manufacturer– for example, autostereoscopic displays

• Philips 423D6W 42 inch (3 meters=5x height)

• Alioscopy 40 inch (more than 4 meters = 7x height)


General Viewing Conditions Depth rendering

• Human perceptual factor– Threshold for Depth Of Focus and binocular

disparity.• 0.2 diopter or 0.3 diopter DOF

• 60 arcmin binocular disparity


+0.2 diopter -0.2 diopter

Comfortable viewing zone

I can not fuse the image and I feel uncomfortable.

Test method

• Subjectively measured quality indicator– Additional indicator besides image quality, e.g.

Naturalness, Presence, Visual Experience

• Visual discomfort– Questionnaires for visual discomfort

– objective measurement of visual fatigue


Depth rendering of 3D Display


Stereoscopic voxel0 -1 -2 -3 -41234

Depth plane

65mm

viewing distance

pixel

Definition of Depth Rendering Ability

• the number of depth planes that can be represented within a comfortable viewing zone of display.

• Parameters affect the depth rendering ability:– Size of comfortable viewing zone– Maximum uncrossed disparity in pixels– Angular depth plane interval

• Parameters affect immerse experience– Field of view(Horizontal visual angel)


background foregroundb fZ Z

maxbD

angularQ

background D foregroundb fD


e

d viewing distance

0 -1 -2 -3 -41234

1, if 5

110.2,

10.2

, if 5

f b

d dZ d Z

ddd

Comfortable viewing zonefZbZ

max / 10b wD e p

Maximum uncrossed disparity in pixels

4bD 4fD Depth rendering ability in pixels

,( ) ( )

f bf b

f w b w

Z e Z eD D

d Z p Z d p

pixel widthwp

1 12 [tan ( ) tan ( )]2 2

wangular

e peQ

d d

Angular depth interval

Screen Filed of view

Comparison of the depth rendering abilities for different displays




Visual threshold0.8 arcmin

Visual threshold0.8 arcmin

Visual threshold30 degree

Visual threshold30 degree

Discussion • Best system discussed:

– 2 projector Full resolution solution 100 inches.• Small size display needs larger comfortable viewing zone

– longer viewing distances may be useful• Autostereoscopic display may show depth quantization effect

– longer viewing distances or higher resolution panel may be advised.

• 2K cinema screen have poor depth rendering ability– higher resolution(now 4K, future 8K) may be strongly suggested.

• Depth rendering abilities vary largely(*)– Content disparity should be adjusted to the display used.


Cinema Content to Home Display


Cinema screen 8 meter height

infin

ite

8 pixels 14 pixelsDirectly use

4.9 m

43 pixels

infin

ite

8 pixels43 pixels

Poor depth perception

1.78 m16 m

2 projectors screen1.35 meter height

Conclusion

• We discussed about various new requirements for subjective video quality assessment of 3DTV.– The requirement of new subjective methodology

is urgent!• We proposed an novel notion depth rendering ability

combing physical parameters and perceptual constrains of 3D display.– identify the 3D display depth rendering

performance– select the appropriate content for certain display


Thank you! Question?


new requirement of subjective video quality assessment methodologies for 3dtv wei chen(*) 1,2,...

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