While image maps are less commonly used than they once were, they can still be useful in some situations. An image map is a good idea when you want to create interactive elements within a visual image, such as a map, diagram, or product picture. Different areas of the image can be clicked to access specific information or links, making the content more engaging and visually appealing. This is especially true when the information is best conveyed through a visual layout rather than text alone.
An image map is a graphical image divided into clickable regions. While they can look nice, they can present accessibility barriers for users with visual impairments or those using screen readers.
There are two types of image maps - client-side and server-side.
"Server-side maps are inherently less accessible, both because they require that the user be able to see the image to discern the regions and also because they require that the user be able to click on the image in an exact spot.
Client-side maps make use of an associated map element to define the clickable regions. Each region is specified in an area element, and each area should include an alt attribute that indicates its purpose so that non-visual users can easily discover the functionality. Assistive technologies allow users to iterate over these areas, making them a much friendlier option than server-side maps and without requiring intrusive fallbacks.
Server-side maps provide no additional functionality, so their use is never recommended." ~ Daisy Consortium, Image Maps
As stated in the article titled Pros and Cons of Image Maps, "The best use of an image map is for, well, a map." So, if you find yourself creating an interactive map by using an image map, there are a few key accessibility considerations you will want to keep in mind:
- Keep It Simple: Avoid overly complex image maps with many small, overlapping areas.
- Use ALT text: This provides a textual description of the image for users who cannot see it.
- "For image maps, text alternatives are needed on both the <img> element itself (to convey the informative context) and on each of the <area> elements (to convey the link destination or the action that will be initiated if the link is followed)." ~ W3C, WAI Tutorials - Image Maps
- Use ARIA: Use the aria-label or aria-labelledby attribute within each <area> element to provide a descriptive text for each clickable region on the image map.
- Keyboard Navigation: Ensure that the image map is keyboard-navigable. This can be achieved using appropriate HTML and CSS to make the area elements focusable.
- Provide Clear Visual Cues:
- Use simple shapes and proper coordinate order. - Use shapes like rect and circle that are easier to interpret by screen readers. Ensure coordinates are listed in a logical order (e.g., top-left to bottom-right for rectangles).
- Ensure the shape (target size) meets WCAG.
- Do not use color alone to indicate clickable area.
- Use proper color contrast. - If the colors of the <area> elements are not sufficiently contrasting with the background, it may be difficult for users with visual impairments to distinguish them.
- Testing with Screen Readers: The best way to evaluate an image map's accessibility is to test it with various screen readers and assistive technologies. This will help identify potential issues and ensure the content is accessible to all users.
Following these guidelines can help you create an accessible image map that is usable by a broader range of people, including those with disabilities.