Collaborative Environments: Accessibility and Usability for Users with Special Needs - Community-Built Databases: Research and Development - page 331

Fig. 13.3 Simplification of a leaf image for different user profiles
who would most appreciate a line drawing with strong contrasting background.
Therefore, simplification algorithms, based on the Canny method [ 5 ], have been
developed so that any color or gray scale image can be converted, automatically
and relying on the user profile, into another simplified one. Fig. 13.3 provides few
examples of simplification of a leaf image obtained through the algorithm. Since
providing these alternative images can be time consuming, their storage has been
coupled with the storage of a corresponding matrix representing the edges contained
within. This matrix is exploited in the Canny algorithmwhen image simplification is
required, thereby reducing the computational efforts. By introducing this feature
within VisualPedia, we have addressed guidelines 1.3 and 1.4 of WCAG 2.0.
Retrieval of educational objects . Retrieval facilities that take the user's profile
into account to rank and return educational objects have been introduced. For each
educational object, the available description matching the user profile is returned,
sorted according to the resultant ranking. The snippet associated with each link also
contains information on the classification of the educational object, i.e., the subject
it belongs to and the school level for which the educational object is more suitable.
In addition to the retrieval facility, educational objects in VisualPedia can be
accessed by following proper links available from the initial pages of the system.
Through this feature, we have addressed guideline 2.4 of WCAG 2.0 for the
navigation on the Web site (Table 13.4 ).
13.4.3 VisualPedia's Usability and Accessibility Characteristics
The strategy applied in the design and development of VisualPedia follows the star
life-cycle model [ 13 ], in that incremental prototype techniques are applied and
evaluations of the prototype at each incremental step are performed. Specifically, in
the case of collaborative design and development of software, the cycle becomes an
evolving and never-ending process, in that the use of the prototypes by the users
suggests new way of use and therefore leads to redesign [ 1 ]. In this framework, at
each step of development, the prototypes are evaluated by discount evaluation
techniques [ 20 ], by experiments, and by informal meetings with novice users.
During these meetings, users are asked to have a look at the current prototype
and to use it. Usability problems are identified by the observation of their activities
and direct feedbacks are collected thanks to a final interview.