Tactile sheets: using engraved paper overlays to facilitate access to a digital document's layout and logical structure

Touchscreen devices (e.g., smartphones, tablets) are a major means of accessing digital resources. However, touchscreen accessibility remains a challenge for users with visual impairments. Mainstream solutions implicitly favor a sequential navigation of digital information. This precludes users from enjoying the advantages of well laid-out, visually-structured documents, especially for certain tasks (e.g., text navigation). In this paper, we introduce tactile sheets---engraved paper sheets that represent the layout of a specific page and that are used as an overlay on a capacitive touchscreen device. Via engraved tactile patterns and textures, users can locate and discriminate different content areas, navigate the spatially-distributed content non-sequentially and access speech feedback with gestures. We report a comparative study with nine visually-impaired users that investigates the technical feasibility and the usability of this approach. Specifically, we compared a mainstream screen reader and two different types of tactile sheets. A similar level of usability is achieved between conditions. Also, participants' qualitative feedback provides strong arguments for the use of tactile pattern overlays. Finally, we introduce a processing pipeline for automatically create tactile sheets based on an existing e-book.