Provide meaningful text equivalents for all non-text elements:
How do you do this?
- Provide a text description for images, pictures, graphics, animations
(e.g., animated GIFs), applets and programmatic objects, ascii
art, frames, scripts, images used as list bullets, spacers, graphical
buttons, sounds (played with or without user interaction), stand-alone
audio files, audio tracks of video, and video incorporated within
html content pages (W3C
Techniques for text equivalents)
- For 'IMG' elements, a textual description may be provided in
the 'alt=' attribute. However, if the image is provided purely
as 'page furniture' or to space out the page elements, then the
appropriate "alt" value is a space, [alt=" "].
Using alt="" (no space) will be interpreted by screen
readers as a missing alt tag. (W3C
Techniques for alt text)
- In alt attributes, indicate what the image DOES, not what it
IS, eg 'Home page, Company name' is more informative for a blind
user navigating your site than 'Company logo'
- Where ALT may not convey sufficient information (if description
longer than 150 characters), use the LONG DESC tag - for example,
for graphs, charts, or use a d-link (link to page containing the
description) (W3C
Techniques for long descriptions)
WHY? Alternative text gives the computer something
to present to the user if they have turned off image-loading in
their Web browsers, those using text-based browsers like Lynx,
and people who are using a screen
reader to read the contents of the screen. Applets require
an alt tag because the user may not have a Java-capable browser
or
may have disabled Java.
As long as the alt tag is present, even if it is empty (alt="", with no space) it can
be interpreted by more recent screen
readers as an alt tag. If the tag is missing altogether, screen readers
may read out the image filename (which is not easy to listen to
and is not often informative).
Next Tip: Provide
text equivalents for multi-media elements
These tips may be applied to any web site or Vista
course, and are derived from the World Wide Web Consortium
(W3C) Web
Accessibility Initiative but are not intended to reinterpret
them. Web developers are encouraged to access the W3C
Web Content Accessibility Guidelines Version 1.0, directly.
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