Digital Signal Processing Reference
In-Depth Information
understanding of the impact of 3DTV on the Human Visual System (HVS).
Some work has already been carried out to establish models that relate
compressed video quality to the Quality of Experience (see Chapter 6).
Additional work on topics such as Just Noticeable Difference (JND) is also
helpful in aiding video compression algorithms. JND can help a compression
algorithm retain perceptually important depth differences.
All of the above are important, and further work on these topics is needed
to help improve 3D video quality. However, probably the most important
factor in ensuring the success of 3D video is understanding visual comfort
and fatigue. There is already a considerable body of knowledge concerning
issues such as accommodation-convergence mismatch (see Section 6.2). What
is missing are reliable methods to automatically take into account such issues
when creating 3D content, and when displaying 3D content. This is a
particular problem for 3DTV, because an important factor in ensuring visual
comfort is making sure that the disparity between two stereoscopic images
is not too large. Whether the disparity is too large depends upon the screen
size, and the distance from the screen. Therefore, calibration is required to
match a screen to its viewing environment.
Cinemas are a controlled environment, which can be carefully calibrated
to ensure visual comfort.
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For the home, calibration should take place with
as minimum user input as possible. Ideally, a 3DTV should detect viewer
positions and change the disparity between the two views so that all viewers
can watch comfortably. The major issue here is to try and take knowledge
of visual comfort and produce a mathematical model that can be used by a
3DTV. Such a mathematical model can also be used in content production
tools, so that content creators can understand the type of viewing conditions
in which their raw captured content is suitable. In post-production, content
creators can make adjustments to their content to optimize it for a particular
environment (e.g. cinema or home use).
7.2.2 DisplayTechnologies
The most widespread technologies rely on wearing glasses. There are a
number of issues with glasses-based technology:
Both polarizing and shutter glasses reduce the amount of light reaching
the eye.
•
A significant number of people do not like to wear 3D glasses, due to
physical discomfort or for aesthetic reasons.
•
3D glasses are perhaps more of a problem for 3DTV than cinema, when one
considers the differences between how the content is consumed. Television
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Although cinemas can be carefully calibrated, the wide range of viewing positions means that
they are not necessarily ideal environments for comfortable viewing of 3D video.
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