Guideline 1.4 Make it easy to distinguish foreground information from background images or sounds.

Level 1 Success Criteria for Guideline 1.4

  1. Any text that is presented over a background image, color or text can be derived programmatically. [I]


Images of text that meets guideline 1.1 should satisfy this criterion. (Refer to Guideline 1.1 Provide text alternatives for all non-text content. )

Level 2 Success Criteria for Guideline 1.4

  1. Text and diagrams that are presented over a background image, color, or text have a contrast greater than X1 where the whiter element is at least Y1 as measured by _____. [V]
  2. Text that is presented over a background pattern of lines which are within 500% +/- of the stem width of the characters or their serifs must have a contrast between the characters and the lines that is greater than X2, where the whiter element is at least Y2. [V]
  3. Users can disable background audio that plays automatically on a page so that it does not interfere with text reading software they may be using. [V]

Editorial Note: The working group is seeking an algorithm that measures contrast in a way that is accurate and testable enough that we could include it in the guidelines. One algorithm, which comes from the Techniques For Accessibility Evaluation And Repair Tools document, is currently under consideration for inclusion in the techniques, but the group has not yet found something that is specific enough to be included at the guidelines level.

Level 3 Success Criteria for Guideline 1.4

  1. Text is not presented over any background (image, text, color or pattern), or if any background is present, the contrast between the text and the background is greater than X2. [V]
  2. Audio content does not contain background sounds or the background sounds are at least 20 decibels lower than the foreground audio content, with the exception of occasional sound effects. [V]


A 20 decibel difference in sound level is roughly 4 times quieter (or louder). Background sound that meets this requirement will be approximately four times (4x) quieter than the foreground audio content.

Who Benefits from Guideline 1.4 (Informative)

  • Individuals with low vision can easily read characters in the content even if they don't have the wide field of view or full range of color perception used by fully sighted persons to separate text from background images.

  • Individuals with hearing impairments that limit their ability to hear all of the frequencies of speech can make out the words from the sounds they can hear because they are not mixed with residual sounds from the music.

Examples of Guideline 1.4 (Informative)

  • Example 1: a background image on a page.

    A background image and text are arranged so that there is no image behind the text or the image is so faint that the difference between the darkest part of the image and the text (which is dark) meets the standard foreground/background contrast requirements. The image behind the text also does not contain lines that are about the same width as the characters so they do not interfere with character recognition.

  • Example 2: speech over background sounds.

    Because speech is often naturally mixed with background sounds (movies, live news etc) and cannot be easily removed or separated, captions are provided (under guideline 1.2) to make dialog understandable. However not all people can see or read the captions. Where speech is mixed or recorded so that it is at least 20 db above any background sounds, most people do not need to rely on captions to understand the dialog.

Appendix A Glossary

background image

Images that appears behind or to the back of the visual field.

derived programmatically

derived programmatically means that the specific value can be determined in a standard, machine or software readable form .

programmatically located

Programmatically located means that the value can be found, though there may be multiple possible values (for example, providing a dictionary definition for a word that has multiple meanings). This term contrasts derived programmatically, where the specific value can be determined.

Editorial Note: This provision is dependent on the definition of a standard way to associate dictionaries and the availability of on-line dictionaries.