Images
When using images on a page, you must provide an alternate method for that content. This can be provided in multiple ways. You can provide this information with a caption, alt
attribute (alt
tag), title
attribute, or aria-label
attribute. If an image has text, all the text in the image must be provided in the alternate content. No matter which method is used, an alt
or title attribute must be provided, even if the attribute is blank.
Testing
- Using the web developer tool, select images > Display Alt Attributes & Outline All Images.
- Inspect each
alt
attribute for the following:- A unique description of the image is provided
- Repeated images used for controls, status indicators, or other programmatic elements have consistent
alt
text - Text included in the image should be included in the
alt
when they are important to understanding the image- Note: DHS Trusted Tester requires all text in an image be included in the
alt
attribute
- Note: DHS Trusted Tester requires all text in an image be included in the
- "Image of" or "Photo of" is not used
- If the
alt
attribute is empty, ensure the image is purely decorative- If the image is not decorative, make sure the image is described on the page
- Check outlined images without
alt
attribute by doing the following:- Right click the image
- Select 'Inspect Element'
- Check for a title attribute for the information normally found on the
alt
attribute
Examples
Correct
<img src="img/warning-sign.jpg" alt="Warning do not read this sign">
Preferred method for providing alternate content. Clear
alt
attribute with all text included.
<img src="img/warning-sign.jpg" title="Warning do not read this sign">
Acceptable, but less compatible with certain assistive technologies. Clear title attribute with all text included.
Warning do not read this sign
<img src="img/warning-sign.jpg" alt="">
<span>Warning do not read this sign</span>
Information contained in the image is provided on the page. In most instances, an
alt
attribute would be preferred. Images marked with an emptyalt
(alt=""
) are considered "Decorative" and not read by AT.
Incorrect
<img src="img/warning-sign.jpg">
Image is missing an
alt
attribute and alternative content
<img src="img/warning-sign.jpg" alt="sign">
Alt
attribute is missing text from image
<img src="img/warning-sign.jpg" alt="Image of sign that says WARNING DO NOT READ THIS SIGN">
Avoid using "Image of" or "Picture of" as the screen reader will notify the user that it's an image. Also avoid using all caps as some screen readers will read each letter, i.e. W-A-R-N-I-N-G.