USERLab Work on the Cration of Text Alternatives for Images
USERLab has conducted extensive work to help developers create good text alternatives (including alt text) for images.
ISO/IEC 20071-11 Guidance for alternative text for imagesLisa Tang and Jim Carter led the development of ISO/IEC TS 20071-11:2012
Information technology -- User interface component accessibility --
Part 11: Guidance for alternative text for images within ISO/IEC
JTC1/SC35/WG6 User interface accessibility. This work was supported by
grants from Microsoft Canada.
The introduction to ISO/IEC TS 20071-11 states:
The saying that "A picture is worth a
thousand words" recognizes that images can present a wealth of
information. It is important that alternative textual descriptions or representations
be used to present the user with a comprehensive account of the purpose and
content of images to people unable to see or interpret them.
Text alternatives help people who cannot
see the images to understand what the image is of or the purpose it serves by
providing the same information in textual form. Text alternatives can be useful
to those with visual impairments, those who turned images off in order to
improve webpage loading speeds, and those who cannot understand the image being
displayed. This document provides guidance for web and document developers to
help them create informative descriptions for various types of illustrations
This international Technical Specification contains:
- a recognition that there are many possible ways for providing text alternatives, including within
- the main document text, where it is readily available to all readers of the document
- primary alternative text (such as that provided by the "alt" tag in HTML) that is primarily available to users of screen readers
alterntive text (such as that provided by the "longdesc" tag in HTML)
that is primarily available to users of screen readers
procedure for creating text alternatives, including many detailed
questions that should be asked of an image and its components
- guidance on identifying the level of importance of different answers to these questions relating to an image or its components
- guidance on writing and evaluating text alternatives
Text Alternatives Tool for Images (TATI)Jim
Carter and Lisa Tang developed a tool that can help developers to
fulfill and go beyond all of the requirements and recommendations of
ISO/IEC 20071-11, Text Alternatives Tool for Images (TATI).
This tool is freely available hosted by USRELab and can be used without
any previous knowledge regarding ISO/IEC 20071-11. Organizations can
also obtain a copy of this tool to install on their own system. This
work was supported by the E. (Ben) and Mary Hochhausen Access Technology Research Award of the Canadian National Institute for the Blind.
This tool contains:
- detailed instructions on how to use the tool
- a page to establish an account so that your work can be saved and retrieved
- a page to identify the image you are describing and document that contains it
- a page for describing the image and its components (making use of the questions and information levels from ISO/IEC 20071-11)
- a page that helps allocate these answers to different possible locations (e.g. the main text, the caption, primary alternative text, etc.)
- a page that organizes the results by allocated location and allows tracking of their being implemented in those locations
- a page that supports administration of the tool within an organization
USERLab Accessibility Demonstration Exercise on Creating Text AlternativesUSERLab
Accessibility Demonstration Experiences (ADEs) are "interactive
exercises designed to be delivered via the web to introduce people to
various aspects of computer accessibility" in about an hour. These
exercises are designed to help people understand the needs and
expectations of users with disabilities, rather than to become experts
in issues and technologies. The USERLab Accessibility
Demonstration Exercise on Creating Text Alternatives aquaints people with the need for text alternatives and the use of TATI in helping to create good text alternatives.
Lisa Tang's PhD Dissertation on Producing Informative Text Alternatives for ImagesThe PhD dissertation of Lisa Tang on Producing Informative Text Alternaties for Images provided the basis of ISO/IEC 20071-11 and of TATI. This work was supported by grants from Microsoft Canada.
This dissertation contains:
analysis of the existing work and guidance regarding text alternatives
and other research into describing visual information in other
- an initial procedure based on these findings for identifying relevant information about images and their components
- research on how well developers, without the help of a procedure or guidance, produce text alternatives
- research on
how well people in various roles, when provided with with a written
procedure and guidance, produce text alternatives
- research on how well people in various roles, when required to follow a procedure and guidance, produce text alternatives
Please note: This page does not use fancy frames or tables in
increase its accessibility to individuals with special needs.