Images and graphics make content more pleasant an easier to understand for many people, and in particular those with cognitive and learning disabilities.
They serve as cues that are used by people with visual impairments, including people with low vision, to orient themselves in the content.
However, images are used extensively on websites and can create major barriers when they are not accessible.
Accessible images are beneficial in many situations, such as:
- People using screen readers: the text alt can be read aloud or rendered as Braille
- People using speech input software: users can put he focus onto a button or linked image with a single voice command
- People browsing speech-enabled website: the text alternative can be read aloud
- Search engine optimization: images become indexed by search engines
How to create accessible images:
- Size your images
- Use proper formatting
- Use Alt tags
- Informative images: images that graphically represent concepts and information, typically pictures, photos, and illustrations. The text alternative should be at least a short description conveying the essential information presented by the image.
- Decorative images: provide a null text alternative (alt=””) when the only purpose of an image is to add visual decoration to the page, rather than to convey information that is important to understanding the page.
- Images of text: readable text is sometimes presented within an image. If the image is not a logo, avoid text in images. However, if images of text are used, the text alternative should contain the same words as in the images.
- Complex images such as graphs and diagrams: To convey data or detailed information, provide a full-text equivalent of the data or information provided in the image as the text alternative.