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Testing for Section 508 Compliance — Accessible Images and Graphics (a)

Section 508 §1194.22 text

(a) A text equivalent for every non-text element shall be provided (e.g., via "alt", "longdesc", or in element content).

Basic Unit Testing

Testing for Accessible Images and Graphics can be one of the few items that can be tested objectively. At its most simple implementation, this standard requires that every <img> tag have an alt attribute. For the developer, this can be as efficient as doing a find for "<img"command in whatever development tool being used with a {alt=""} - no braces needed - in the clipboard to paste into each tag. Then the developer only has to add any text for graphics that provide information. All Accessibility testing tools will test for this feature. The National Center for Accessible Media has a free Accessibility QA Favelet with a variety of testing tools. Their image option provides an simple list of all the images on the page with the alt text and a copy of the image for convenient verification that the image has the correct text.

QA Testing — What to Look For

All images have an ALT attribute
An image with no ALT attribute will usually speak the name of the file, in some versions, the path and the name of the file. This is particularly obnoxious for spacer images.
Images that do not convey information have a null ALT attribute <img alt="">
This convention is not spoken by the screen readers. It should be used for bullets, icons, lines, decorative photos and all other graphic elements that do not convey information to the user.
Images that do convey information are clearly described.
Use clear and simple text. Describe the information, not the appearance.
Check the spelling and grammar of the descriptive text.
Spelling errors are very puzzling to the listener, as the screen reader tries to guess how the word is pronounced. It may spell out the word. Insure that the grammar is clearly understood.
Long description
The ALT attribute should not exceed 80 characters. Images that need a longer description can use the LONGDESC attribute which gives a URL directing the listener to an HTML page with a more complete description of the image.

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More Information

Web Accessibility Toolbar
An toolbar for Internet Explorer with many useful Accessibility tests and tools, including: images, validation, style sheets, gray scale and references.
Web Developer
An extension to Mozilla's FireFox browser providing validation, images, CSS,Forms,Outline, Disable, and resize tools.
Checky Firefox extension
An extension to Mozilla's Firefox with pull down menu access to major on-line accessibility and validation checkers.
 
Accessibility QA Favelet
a series of accessibility test tools including images, forms, tables, grayscale, style sheets.