Information Technology Reference
In-Depth Information
expected that at least 60 fps and up to 120 fps of temporal resolution is probably
needed for UHD video since the present television broadcasting adopts an inter-
lace signal and 60 fields per second is used in practice. If the temporal interval be-
tween frames is shortened, Motion Prediction of video coding will become more
effective, and it should result in increased compression efficiency
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Gazing viewing
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Guidance viewing angle
(*)The figure is modified from [21].
Fig. 44
The information acceptance characteristic within view [21]
4.1.1.3 Gradation per pixel
If the gradation per pixel increases, the contrast in the dark portions of a screen can
be more visible. Moreover, there is also an advantage which can perform high pre-
cision calculations in the filter processing and the sub pixel processing for Motion
Prediction in video coding. Therefore, the quality improvement of video is ex-
pected to be improved by increasing bit depth from the present 8 bpp to 10-12 bpp.
4.1.1.4 Color space
Although the amount of information becomes 1.5-2 times by increasing the color
sampling format from 4:2:0/4:2:2 to 4:4:4, the possibility to use 4:4:4 format will in-
crease if the compression efficiency of video coding is improved. Since the number
of the signal elements of 4:2:0 format is one fourth of that of 4:4:4 format for
chrominance signal, there is a trade-off in quality for video coding. At low bit rates,
4:2:0 video is preferred over 4:4:4 video since it contains fewer pixels. On the other
hand, at higher bit rates, 4:4:4 video is preferred over 4:2:0 video. As a result, there
is a cross-over point on performance between 4:2:0 and 4:4:4 video coding. For ex-
ample, even if the cross-over point between 4:2:0 and 4:4:4 formats occurs at a
higher bit rate than that of the practical use with existing video coding technology,
