Creating Quality Image Descriptions
Images generally need alternative text for assistive technology. The alternative text is read by screen readers to describe images to users, and displays in place of the image should it fail to load. It is also indexed by search engines that are crawling the page. Writing good alt text takes some effort; pay attention to the context of the image as that will determine the level of detail needed to describe it. Here are some quick tips:
If you’re using a caption on an image, avoid any redundancy between the alt text and the image caption. The alt text can be less descriptive in this case because it has the supporting caption text.
If the image falls within a paragraph, think about the context of the image. The more thoroughly the surrounding text describes the image, the more brief your alt text can be.
Never use a phrase like “image of…” because it is unnecessary. The user already knows you are describing an image in this case.
Alt text should be brief enough to convey the visual information not contained elsewhere in the text.
If the image also serves as a link, do not include a phrase like, “link to…” because the screen reader will identify the link before reading the alt text.