A screen reader can read or access an image only through the image’s alternative text (alt text). If an image contains text, a screen reader can only read the text if it’s mentioned in the alt text too.
It is essential to recognize that people with vision impairments use the internet differently than those who are sighted.
For instance, when a sighted person views the contents of a PDF document, they simply open it and access the content visually.
However, assistive technologies such as screen readers are often necessary for those with vision impairments to access the same information. These tools help to make the internet more accessible for everyone, regardless of their abilities.
When a PDF document is not accessible, assistive technology such as screen readers won’t be able to read its content. Although screen readers can open and read the content of a PDF document aloud, it is essential to ensure that the PDF is accessible for assistive technology to function correctly and read out the PDF the way it’s meant to be.
Can screen readers read images?
Screen readers generally cannot directly “read” images like they can with text. A sighted user can access the content of an image by simply looking at it, but a screen reader accesses the image only through the alternative text (alt text) or descriptions provided for images.
Alt text is added to the HTML code of a web page or document, and it provides a textual description of the image’s content or function.
When a screen reader encounters an image with alt text, it reads the alt text aloud to the user, allowing them to understand the image’s purpose or content.
But alt text of an image doesn’t just contribute to making the image accessible; it also offers two significant benefits:
- Browsers display the alt-text instead of the image if the file does not load or if the viewer is not viewing images.
- Search engines use the alt-text description to determine the content of the image.
You might want to visit our in-depth article outlining essential guidelines related to writing alt text the correct way.
Can screen readers read the text in images?
Screen readers can read an image only through its alt text, but if the image contains textual information, like a graph, chart, or infographic, screen readers won’t be able to read the text within the image.
For example, consider the following image:
As you can see, it contains textual information. A screen reader won’t be able to access the information presented in this image.
Therefore, a possible alt text of this image can be:
“Webinar’s cover photo that says “The Future of Artificial Intelligence in Accessibility”
Note that appropriate alt-text should convey the same information to sighted viewers and screen reader users, serving the author’s purpose. There is no right or wrong answer.
Describing images with meaningful alt text is crucial for web accessibility, allowing individuals who are blind or have low vision to access the same information and context as sighted users from visual content.