All images, either standalone or embedded in a document or slide deck, need to have alternative text (commonly called “alt text”) that describes the content and function of the image.
General Guidelines for Writing Good Alt Text¶
Be concise: Summarize the content and function of the image with a few short sentences. Avoid starting the alt text with “Image of...” or “Picture of...”.
Provide context: Describe what information the image conveys in the specific context of the document.
Emphasize function: For complex images (e.g., charts and graphs), provide a brief summary in the alt text that highlights the key takeaway (that is, the function of this image).
If an image is purely decorative and does not convey any information, you can simply put “decorative” as the alt text.
Generate Alt Text with AI Tools¶
Writing alt text takes time. Luckily, AI tools can help generate initial drafts of alt text. You still need to review and edit for accuracy and clarity, but AI tools can save significant time.
Upload the image to an AI chatbot (e.g., ChatGPT, Microsoft Copilot). Note that the image should not contain sensitive or private information. Then, give the AI chatbot a prompt like the following:
Generate alternative text for the uploaded image. Keep it concise.
(Optional but recommended) This image is used in the context of [briefly describe the context or topic, e.g., illustrating coordinate transformation].
After the AI chatbot generates the alt text, review and edit it as needed. Do not skip this step!
How to Add Alt Text¶
Depending on the software you are using, the steps to add alt text to an image may vary:
Documents and Slides from Office Applications contains instructions for Microsoft Word/PowerPoint, OpenOffice/LibreOffice, Apple iWork Pages/Keynote, and Google Docs/Slides.
LaTeX-generated Documents contains instructions for LaTeX documents.
Webpages (HTML) contains instructions for HTML webpages.
For software not listed above, generally, you can right-click on the image and look for an option like “Add Alt Text” or “Add Image Description”. Sometimes, this option may be hidden under “Format” or “Properties” on the menu.