This is not a blog post about taking alt text away from screen reader users. It’s a post about making image descriptions available to more people.
What is alt text
Alt text, or ‘alternative text’, is a description, in words, of an image. It goes in the ‘alt text’ field in a software program like PowerPoint or Word, a content management system or social media platform, or directly into the image attributes for images on a website.
Who alt text is for
1. People who use screen reading software
Alt text is read by screen reading software. Not all screen reader users are blind. And not all visually impaired people use screen reading software.
2. It loads when images don’t
Alt text loads if the image it relates to fails to load, for example due to a bad connection or if images are turned off in a browser to save data.
3. Alt text is readable by search engines
Incidentally, being readable by machines means that alt text can be read by search engines and helps with search engine optimisation (SEO).
Who alt text is not for
If images load, alt text is not available for users who navigate visually. That includes magnification users. There are several ways to magnify things on your screen:
- lowering resolution or increasing scaling to make everything as big as possible
- changing the browser zoom level
- changing the size of text in your browser
- using built-in operating system functionality, like Zoom on a Mac or Magnifier on Windows (screen magnification)
- using software, like Zoomtext
None of these read out alt text.
A 2018 WebAIM survey about low vision users found that:
- 48.4% of respondents used screen magnification
- 44% changed their browser zoom level
- 36.7% changed the size of the text in their browser
- 45.2% of respondents used screen reading software
These types of assistive technology can be used in combination, so the results don’t add up to 100%. It’s clear that more visually impaired people use magnification tools than screen reading software. A lot of people may benefit from more visible alt text.
There are many reasons that visually impaired people might prefer magnification over screen reading software. It’s deeply personal, but a few reasons are:
- wanting to use their remaining sight
- being embarrassed about using a screen reader in public
- having difficulty processing electronic voices
- finding magnification tools quicker to learn than screen reading software
Why surfacing alt text matters
Magnification users may struggle with the content of images. Particularly when they’re images of text, graphs or diagrams. Anything intricate or detailed. There may also be issues magnifying images so that they’re big enough to see:
- browser windows have a set width, and browser zoom does not always apply properly to images, or only applies up to a certain level
- apps and devices may restrict how much someone can enlarge an image
- many image formats pixelate when enlarged, which means detail is impossible to see or read
Users who need a bit more help understanding what’s happening in an image, even if they can see it, also don’t get access to alt text unless they’re using a screen reader. It often helps our understanding of images when we get descriptions of what they are. Particularly if it’s a complex image like a diagram.
There’s currently a trend for including image descriptions in posts on LinkedIn. It’s probably for (at least) two reasons:
- Platforms like Twitter/X, Bluesky and Slack actually make the alt visible to everyone with an ALT badge on images. Selecting the badge shows the image description.
- It’s difficult to add alt text to LinkedIn posts. And it’s impossible to add alt text on the mobile app.
It’s great to see image descriptions in posts being normalised.
How to make image descriptions available to everyone
After you’ve written your post and added your image, add an image description in the post body. The standard format to do this is [Image description: and then the description]. I usually add it after the hashtags and just above the image, but if the content of the image is super important you can add it further up.
Remember to convey the meaning of the image. What’s happening? What’s the purpose of showing it? If there’s any text, write it out in full.
Reduce auditory clutter for screen reader users
If you’ve got access to the alt text field, you can write ‘described in post’ if you’ve added a full image description. This saves screen reader users from getting the same information twice.
You don’t need to start the alt text field with ‘image’ or ‘photo’. Different screen readers use different words, but they’ll always announce that it’s an ‘image’ or ‘graphic’, as long as there’s something in the alt text field.
To learn more
To learn more about describing images, join Content Design Ireland’s Accessible Content Design course.
Statistics from WebAIM’s 2018 survey about low vision users.