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M16758 – Influence of views and depth compression onto quality
of synthesized views
July, 2009, London
Krzysztof WegnerKrzysztof Klimaszewski
Marek Domański
team supervisor: Marek DomańskiChair of Multimedia Telecommunications and Microelectronics
Poznań University of Technology, Poland
M16758 – Influence of views 2
Multiview system
RectificationCorrection
Depth M apEstim ation
V iewSynthesis
Rendering
V iew and Depth M ap
Transm ission
D isplay
Com
pres
sion
Dec
ompr
essi
on
M16758 – Influence of views 3
Multiview system
RectificationCorrection
Depth M apEstim ation
V iewSynthesis
Rendering
V iew and Depth M ap
Transm ission
D isplay
Com
pres
sion
Dec
ompr
essi
on
M16758 – Influence of views 4
Depth map compression issues
How to compress depth maps? Can MVC be used?
How to share bandwidth between views and depth maps? Which one is more important? What is the optimal ratio?
M16758 – Influence of views 5
Depth map features Differences between depth maps and
viewsDepth Maps Viewsonly one color
componentthree color
componentslimited texture abundance of texture
prominent contoursless prominent
contoursaccurate depth value
importantaccurate value not
necessary
M16758 – Influence of views 6
Depth map decimation What is the influence of depth map
decimation on the view synthesis process?
1024
76 8
x2
1024
76 8
512
384
256
192x4
M16758 – Influence of views 7
Test setup
M VCC om pression
ViewSynthesis
A
B
C
M VCC om pression
M VCD ecom pression
M VCD ecom pression
D epth M aps
ViewsView A
View C
Depth M ap A
Depth M ap C
Transm
ission B'
M16758 – Influence of views 8
View quality measurement
M VCC om pression
ViewSynthesis
A
B
C
M VCC om pression
M VCD ecom pression
M VCD ecom pression
D epth M aps
ViewsView A
View C
Depth M ap A
Depth M ap C
Transm
ission B'
M16758 – Influence of views 9
Cameras and software The following software and camera
numbers were used:
Data setOriginal pair (A
and C)Synthesized
view (B)Book
Arrival7 and 10 8
Pantomime 38 and 41 39Newspaper 3 and 6 4
VSRS version 3DERS version 3JMVC version 3
M16758 – Influence of views 10
Results Synthesis quality for UNCOMPRESSED
view and depth map
Data setPSNR using
uncompressed data [dB]
PSNR using uncompressed data
(depth maps decimated with factor 2)
[dB]
Book Arrival 36.1787 36.1865
Pantomime 35.5908 35.6526
Newspaper 29.2191 29.3317
M16758 – Influence of views 11
Results Results for compressed data – Book
Arrival
0 500000 1000000 1500000 2000000 2500000 3000000 3500000
31
32
33
34
35
36
37
PSNR of synthesized view against total bitrate
2121 dec 2x21 dec 4x2626 dec 2x26 dec 4x3131 dec 2x31 dec 4x3636 dec 2x36 dec 4x
Bitrate [bps]
PS
NR
[dB
]
M16758 – Influence of views 12
Results Results for compressed data – Book
Arrival
-0.1 0.0999999999999999 0.3 0.5 0.7
31
32
33
34
35
36
37
PSNR of synthesized view against bitrate ratio
2121 dec 2x21 dec 4x2626 dec 2x26 dec 4x3131 dec 2x31 dec 4x3636 dec 2x36 dec 4x
Ratio
PS
NR
[dB
]
M16758 – Influence of views 13
Results Results for compressed data –
Pantomime
1000000 2000000 3000000 4000000 5000000 6000000 7000000 8000000 9000000 10000000 11000000
33
33.5
34
34.5
35
35.5
PSNR of synthesized view against total bitrate
2121 dec 2x2626 dec 2x3131 dec 2x3636 dec 2x
Bitrate [bps]
PS
NR
[dB
]
M16758 – Influence of views 14
Results Results for compressed data –
Pantomime
0 0.1 0.2 0.3 0.4 0.5 0.6
33
33.5
34
34.5
35
35.5
PSNR of synthesized view against bitrate ratio
2121 dec 2x2626 dec 2x3131 dec 2x3636 dec 2x
Ratio
PS
NR
[dB
]
M16758 – Influence of views 15
Results Results for compressed data –
Newspaper
0 1000000 2000000 3000000 4000000 5000000 6000000 7000000 8000000
27.7000
27.9000
28.1000
28.3000
28.5000
28.7000
28.9000
29.1000
29.3000
PSNR of synthesized view against total bitrate
2121 dec 2x2626 dec 2x3131 dec 2x3636 dec 2x
Bitrate [bps]
PS
NR
[dB
]
M16758 – Influence of views 16
Results Results for compressed data –
Newspaper
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
27.7000
27.9000
28.1000
28.3000
28.5000
28.7000
28.9000
29.1000
29.3000
PSNR of synthesized view against bitrate ratio
2121 dec 2x2626 dec 2x3131 dec 2x3636 dec 2x
Ratio
PS
NR
[dB
]
Subjective tests
A single-stimulus test was conducted 15 spectators quality was rated from
5 (“imperceptible artifacts”) to 0 (“very bad with annoying artifacts”)
The original video from actual real camera was used as hidden reference.
M16758 – Influence of views 17
Optimal QD for depth map
Depth quantization parameter index QD has negligible (less than 0.2 dB decrease) impact on synthesized view quality as long its value is smaller than the following threshold estimated from the experiments
M16758 – Influence of views 21
T hresho ld QD 49 0.005 76 QP 2
M16758 – Influence of views 22
Conclusions 1/2 it is possible to transmit the depth maps using
MVC codec with sufficient quality view quality is much more important than depth
quality in terms of synthesized view quality depth bitrate can be kept as low as 10 - 20 % of
total bitrate without significant loss of synthesized view quality (for decimated depth map)
M16758 – Influence of views 23
Conclusions 2/2
for a certain range of values of quantization parameter index for depth compression (QD) , no change of synthesized view quality is noticeable
higher compression rate with comparable quality can be obtained by decimating the depth map by a factor of 2