A Framework for Blind User Interfacing

At the 10th ICCHP conference held July 12-14, 2006, at the University of Linz, Austria, the staff of Universidad de Madrid, Spain, presented their paper on the development of a framework of graphical dual user interface for blind users.

Blind and visually impaired people usually encounter difficulties while manipulating standard graphic user interfaces. Specific usability requirements are necessary to provide accessibility to blind users. The interface information must be structured in a way that enables the blind users to manipulate the interface efficiently. The meaning of the interface content should be kept intact during the adaptation and the information supplied must be adapted for the assistive devices that will be used by the blind users. Consequently, these requirements have an impact on HCI modeling which involves creation and designing of the task, domain, dialog, presentation, platform and user interface models. Apart from these, the paper describes a framework for developing graphical user interfaces for blind people based on usability requirements such as task adequacy, dimensional trade-off, maintenance of behavior equivalence, semantic loss avoidance and device independency requirement.

FBLIND (Framework for Blind user Interface Development) is an assistive technology solution that has been created based on these requirements. This framework has three main components: a set of user interface design guidelines, an interface development toolkit that consists of automatically adapted user interface objects (BVCL) and a programming library that provides support for speech, and Braille input and output (SBIO).

The blind user interfacing guidelines incorporated into the framework are based on the recommendations of the Spanish and international standards on software accessibility. These guidelines affect the HCI models to an extent. The important feature of these guidelines is that the application must be compatible with the assistive technologies that blind people use to access graphical user interfaces.

BVCL (Blind user adapted VCL) is a toolkit that incorporates the usability requirements of blind users that are applicable to the presentation, platform and user models. It incorporates user interface objects, which saves development time and eases the programming of additional speech and Braille messages. BVCL configures the specific messages generated in speech and Braille for each user interface object along with incorporating layout managers to automate the layout and sizing of the user interface objects in accordance to the user preferences on font sizes, colors, and other factors.

SBIO is a package for Microsoft Windows and it is the most commonly used platform by blind people. It is made up of a series of programming components that improves speech and Braille input and output. It consists of four components: the Microsoft speech API, a Braille API, Braille interface (SBIO-Core), a set of Active X components that offers a simplified and unified speech, and a dynamic link library (SBIO-Lib).

The use of this framework had been illustrated with the help of DABIN. It is a software environment for bilingual dictionaries with a generic interface combining speech synthesis and Braille for use by blind and sighted users. Its prime function is to search for words in one language and translate them into another language from a range of bilingual dictionaries. The plus of this feature is that users can choose the source and target languages of translation and the user interface language.

This assistive technology solution meets the requirements of both sighted and blind users. The specific usability requirements take into account the difficulties faced by blind users and these requirements have been built into HCI models. The proposed framework improves the development of the user interfaces and includes a set of guidelines that help the developer focus on relevant tasks during the designing of the six HCI models. More tool support can be provided by a CASE tool that covers the whole user interface development life cycle.