Darstellungs- und Interaktionstechniken zur effizienten Nutzung grafischer Oberflächen durch Blinde und Sehbehinderte

Personal computers become more and more important in people's lives. Digital information and user interfaces with high-quality graphical representations facilitate education as well as daily work and entertainment. Also for blind and visually impaired persons, the computer is important to improve their quality of live. It gives them independence and at the same time enhances their integration into society. Due to the increasing use of digital documents, the accessibility of information is raised steadily. By using assistive technologies such as magnification software and screen readers, the presentation of digital documents can be adapted to each user's needs. For printed or handwritten documents, this is not easily possible. However, current technologies still need improvements. Screen readers, for example, present graphical user interfaces only by textual information including the visible textual content as well as some semantic information like the type of a user interface element or its current state. Information on the graphical representation itself is provided only rarely, although this is also useful for the blind. Visually enabled people often use graphical information like color or positioning as means of information or communication. Indeed, for users of magnification software graphical information is available. However, the way of presenting graphical user interfaces often not assists users in an optimal way. For instance, while working with documents to read and edit texts horizontal scrolling is often necessary which significantly stresses the user. Further, through the enlargement of the screen content to multiple screen sizes important parts of the graphical user interfaces are often not visible to the user. Therefore, there is a high risk of missing important information. This thesis contributes to improving the access of blind and visually impaired people to graphical representations. Therefore, state-of-the-art technologies and new methods for improving the adaption of graphical user interfaces and documents as well as new approaches for interactive use and creation of graphics by blind and visually impaired persons themselves were examined. It could be shown that the requirements for presenting graphics to visually impaired persons and blind ones, who use graphical-tactile displays, are basically similar. Based on this finding a framework was developed which can be used to realize tac-tile representations as well as a newly developed screen magnification concept for partially sighted computer users. With respect to the steadily growing group of people with weaker and mostly age-related visual impairment another concept and prototype for screen magnification was developed which requires …