Understanding WCAG 2.0

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Images of Text (No Exception):
Understanding SC 1.4.9

1.4.9 Images of Text (No Exception): Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed. (Level AAA)

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

Intent of this Success Criterion

The intent of this Success Criterion is to enable people who require a particular visual presentation of text to be able to adjust the text presentation as required. This includes people who require the text in a particular font size, foreground and background color, font family, line spacing or alignment.

This means implementing the text in a manner that allows its presentation to be changed or providing a mechanism by which users can select an alternate presentation. Using images of text is an example of an implementation that does not allow users to alter the presentation of the text within it.

In some situations, a particular visual presentation of the text is essential to the information being conveyed. This means that information would be lost without that particular visual presentation. In this case implementing the text in a manner that allows its presentation to be changed is not required. This includes text that demonstrates a particular visual aspect of the text, such as a particular font family, or text that conveys an identity, such as text within a company logo.

Text that is decorative does not require implementing the text in a manner that allows its presentation to be changed.

The definition of image of text contains the note: "Note: This does not include text that is part of a picture that contains significant other visual content." Examples of such pictures include graphs, screenshots, and diagrams which visually convey important information through more than just text.

Specific Benefits of Success Criterion 1.4.9:

  • People with low vision (who may have trouble reading the text with the authored font family, size and/or color).

  • People with visual tracking problems (who may have trouble reading the text with the authored line spacing and/or alignment).

  • People with cognitive disabilities that affect reading.

Examples of Success Criterion 1.4.9

Related Resources

Resources are for information purposes only, no endorsement implied.

Techniques and Failures for Success Criterion 1.4.9 - Images of Text (No Exception)

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. The techniques listed only satisfy the Success Criterion if all of the WCAG 2.0 conformance requirements have been met.

Sufficient Techniques

  1. C22: Using CSS to control visual presentation of text (CSS)

  2. SL31: Using Silverlight Font Properties to Control Text Presentation (Silverlight)

  3. C30: Using CSS to replace text with images of text and providing user interface controls to switch (CSS)

  4. G140: Separating information and structure from presentation to enable different presentations

  5. PDF7: Performing OCR on a scanned PDF document to provide actual text (PDF)

Additional Techniques (Advisory) for 1.4.9

Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.

General Techniques for Non-Decorative Content

  • Using server-side scripts to resize images of text (future link)

CSS Techniques

Common Failures for SC 1.4.9

The following are common mistakes that are considered failures of Success Criterion 1.4.9 by the WCAG Working Group.

(No failures currently documented)

Key Terms

essential

if removed, would fundamentally change the information or functionality of the content, and information and functionality cannot be achieved in another way that would conform

image of text

text that has been rendered in a non-text form (e.g., an image) in order to achieve a particular visual effect

Note: This does not include text that is part of a picture that contains significant other visual content.

Example: A person's name on a nametag in a photograph.

pure decoration

serving only an aesthetic purpose, providing no information, and having no functionality

Note: Text is only purely decorative if the words can be rearranged or substituted without changing their purpose.

Example: The cover page of a dictionary has random words in very light text in the background.

text

sequence of characters that can be programmatically determined, where the sequence is expressing something in human language

This Web page is part of Understanding WCAG 2.0: A guide to understanding and implementing WCAG 2.0. The entire document is also available as a single HTML file. See the The WCAG 2.0 Documents for an explanation of how this document fits in with other Web Content Accessibility Guidelines (WCAG) 2.0 documents. [begin add]To send public comments, please follow the Instructions for Commenting on WCAG 2.0 Documents.[end add]

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