The
goal of this project was to research and
implement tools to generate textual
alternatives such as the ALT attribute in IMG and other graphical HTML
elements.
Often images and some other HTML tags lack a
textual alternative. This makes
them inaccessible to screen readers, non-visual/text-only browsers and
Braille readers.
Adding alternate descriptions for these tags is one important aspect of
making pages more
accessible.
On one hand, the project focuses on HTML authors
with a tool to set ALT texts on
a site-wide per-image basis, instead per each occurrence in HTML
documents. The idea of
this tool is motivate HTML authors to provide ALT text for all images
by facilitating this
job. A graphical (GUI) and command-line (CLI) version of such an
application are
presented.
On the other hand, for users surfing on existing
sites with lack of ALT text, a
filter tool tries to guess ALT text by heuristics. This tool can be
used in a proxy server
or CGI which filters/transforms HTML and reads pages from the original
Web server, inserts
missing ALT text by attempting to "guess" it, and sends them on to the
Web
client.
The heuristics used to guess alternate text range
from looking at an image's
height & width to identify simple cases such as bullets and
rulers, to analyzing
hypertext links for extraction of usefull document link titles. The
project report gives a
detailed description of the implementation and explains design choices.
Keywords:
ALT,
IMG, HTML, C++, Filtering, W3C, WAI, Web,
Accessibility, Braille, Screen Reader, Proxy, CGI, HTML Tool, Blind or
Visually Impaired
People, User Interface Transformation