Online Access

This area contains explorations into online access for the blind.


A variety of assistive technologies are available for the blind readers, including refreshable braille displays and speech synthesis software. These technologies share a variety of limitations when used with document presentation systems (e.g., text editors, web browsers). I'd like to understand (and ideally, help to mitigate) some of these limitations.

2D Structures

Many online documents, whether implicitly or explicitly, contain instances of two-dimensional (2D) structures (e.g., graphs, tables, trees). Computer source code, in particular, makes heavy use of indentation to show hierarchical program structure. It is also common practice to use white space to delineate informal tables, etc. Systems should help blind users to be aware of these structures, support exploration of them, etc.

Styling Markup

The vast majority of online documents (e.g., EPUB, HTML, PDF) contain styling markup. This is used to convey document structure, emphasize words, etc. Unfortunately, this markup is commonly removed when the documents are read aloud, displayed in braille, etc. This is a completely needless loss of semantic information.

For example, the styling could be converted into printed markup. A blind reader would then be able to specify which kinds of styling s/he wishes to "hear about" at a given moment, e.g.:

  • high level (lists, sections, tables, ...)
  • low level (bold, italic, teletype, ...)


Web pages and EPUB documents rely heavily on HTML and CSS markup. It seems quite feasible to capture this information (e.g., in a web browser or text editor extension) and reinterpret it in an explicit format. Here, as a starting point, are some test files:

The Software Notes page is a start on tabulating the results from different software stacks. The CSS Hacks page contains some plausible (but untested!) CSS code to transform HTML tags.

SVG Content

Scalable Vector Graphics (SVG) is an XML-based vector image format for two-dimensional graphics with support for interactivity and animation. The SVG specification is an open standard developed by the World Wide Web Consortium (W3C) since 1999. SVG images and their behaviors are defined in XML text files. This means that they can be searched, indexed, scripted, and compressed. As XML files, SVG images can be created and edited with any text editor, but are more often created with drawing software.

-- Scalable Vector Graphics (WP)

It seems plausible that certain types of SVG content could be processed into blind-accessible versions. For example, plots could be summarized by tables, diagrams could be converted into nodes and arcs, etc.

This wiki page is maintained by Rich Morin, an independent consultant specializing in software design, development, and documentation. Please feel free to email comments, inquiries, suggestions, etc!

Topic revision: r36 - 13 Apr 2016, RichMorin
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