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Visual
Accessibility for Color Vision Deficiency in MPEG-21 |
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2003
. 01 ~ current |
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The vision for MPEG-21 is to define a multimedia framework
to enable transparent and augmented use of multimedia resources
across different communities as well as a wide range of networks
and devices. That is, everyone should be able to easily and
equally access any kinds of digital item. In the MPEG-21, user
accessibility is an important part of multimedia (or digital
item) adaptation.
Specially, MPEG-21 visual accessibility for colored-visual resource
of digital item is proposed to give better accessibility of
color information to people with color vision deficiency (CVD).
We propose an adaptation system for CVD as well as a description
of CVD in MPEG-21.
To convey visual information in multimedia contents, color plays
an important role as a fundamental visual feature that gives
richness to access visual world. Recently, digital multimedia
resources with high-quality color are accessible even with wireless
personal communication devices such as cellular phone and PDA.
Color visual information works well for people with normal color
vision, but not for people with CVD. The use of rich color may
even cause people with CVD to misread the true meaning of visual
information. Although there is no treatment for the CVD, many
still and moving pictures, color documents, and web pages on
Internet have been designed without any consideration about
the problem. |
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Figure 1. Procedure
of digital item adaptation (DIA) |
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In MPEG-21, a digital item is composed of resources and descriptions.
So MPEG-21 DIA is composed of two modules: resource and description
adaptation modules. Upper figure shows DIA procedure in MPEG-21.
As shown in the figure, an engine called 'DIA
engine' performs the adaptation for digital item. The adaptation
procedure for a digital item is as follows. Firstly, original
digital item is delivered from digital item provider to DIA
engine. The DIA engine performs the adaptation of the digital
item, based on DIA description delivered from the digital item
consumer (user). And then the adapted digital item is transferred
to the digital item consumer.
In the DIA engine, the description adaptation module adapts
description (D in Fig) of the original digital item into a new
or modified description (D' in Fig). The resource adaptation
module adapts resource (R in Fig) in the original digital item
into a new or modified resource (D' in Fig). To do so, the DIA
engine needs DIA description containing user characteristics.
In result, the DIA engine can provide equivalent accessibility
of the digital item to user in any kind of environments. |
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Table
1. DIA description for CVD |
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As shown in Table, in TextualDegreeType, 'mild' represents
mild CVD (anomalous trichromat). Similarly, 'severe' represents
severe CVD (dichromat). NumericalDegreeType expresses mild CVD
as the number from 0.0 to 0.9, and severe CVD as the number
1.0 . DIA description containing user's CVD type and severeness
is delivered to DIA engine. The DIA engine performs user-optimal
adaptation according to the DIA description. |
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