Image accessibility guidelines
Use an image description to describe any image you Tweet. An image description (also known as alt text) helps those who can't view the image. Your alt text should be short but descriptive – you have a 1,000-character limit on Twitter, but keep in mind that best practice is to keep it as succint and clear as possible.
Your image description should highlight the relevance of the image to the text it’s supporting. Be sure to capture the action, movement, relationships, visual details, and anything unique in the image. A useful formula to help decide on the copy to use for alt text is Object -> Action -> Context. The object is the main focus of the image. The action describes what’s happening – often what the object is doing. The context describes the surrounding environment. This format keeps the alt text objective, succinct, and descriptive.
When you Tweet photos using the Twitter app for iOS or Android, or on Twitter.com, you have the option of adding an image description. Don't hide information in your images. People who use a screen reader won’t see the information in images or infographics. Make sure the most critical message is included in the text, and use images to complement that text.
Alternatively, you could link to an accessible document or web page with a data table or transcript of the information an infographic contains. This will be accessible to screen reader users.
For more information, visit our help center article on how to make images accessible.