Guidance for writing alternative text for images

(Last updated: 11 October 2024)

Alternative, or 'alt', text is a description of an image in order to make the information it conveys accessible to readers who are unable to view the image.

Why do we ask authors to provide descriptions (alt text) of the images in their work?

• Adding alt text makes your work more accessible to readers who may experience difficulty with visual information.
• Adding alt text improves the discoverability of your work by providing additional text for search engines.
• For readers who do not have sufficient bandwidth on their electronic device to display the image, the alt text will be displayed instead.
• As the author, you are best placed to provide a clear description that takes into account the rest of the work – such as information already given in the text – as well as the purpose and intended audience of the work. This is something that automatic 'generate alt text' functionality can not (yet) accomplish.

Does every image need a description?

You do not need to add a description

• If the description would only provide information that is already given in the caption or the surrounding text. This would for instance apply in the case of video clips or stills of a signed language example that is also given as text with a gloss. Or in the case of a photograph of a street sign, where the text on the sign is already mentioned in the text of the article or the caption of the image.
• For mathematical equations.
• For emojis included as part of the text (i.e., not embedded as an image).
• For tabular materials that are created with the functionality that the word processing software provides. These will remain tables in the published ePub version, and thus be accessible to screen reading software. If tabular material is submitted as an image (as is the case for many concordances), this will require alt text (and probably a long description).

How long can the description be?

For alt text the goal is to stay under 100 words. Alt text on average is ca. 30 words.
If you require more space, you can add a long description in addition to the alt text (not instead of it!).

What should be in the description?

• The description should provide all the information that you want to convey to the reader through the image. The detail depends on the purpose of the image in the context of your text. Do not include information that is not available to those viewing the image.
• Screen reading software indicates that the alt text is the replacement for an image, so you do not need to start with “Image of ...” or “Graphic of ...”. Only add this if the mode of the (source of the) image is relevant, e.g., “Oil painting of ...”.
• Use clear language in natural phrases, in the language of your article/book. Spell check this text like any other part of your text.
• Do not repeat information that is in the caption, or that has already been provided in the text surrounding the image.
• Alt text can not include any formatting (bullet points, italics, hyperlinks, etc.); a long description can include such features.
• Always end the alt text with a full stop/period.

See also examples of specific types of images/graphics below.

A note about describing people in images

In general, demographic information is avoided unless it has a direct impact on the meaning and purpose of the image itself. If not necessary, use generic terms such as ‘a child’, ‘students’, ‘a group of people’, ‘two persons’.

If a specific person is the focal point of the image, and this person cannot be expected to be known to your readership, it is useful to provide details on how they look (age, gender, race). This should only be information that would also be assumed in that way be someone viewing the image and not accessing the alt text.

How to provide us with your descriptions?

It is best to add the alt text descriptions immediately below the captions that are provided so that they are clearly linked. For clarity, you should use “Alt text:” and “Long description:” (where necessary) to introduce each of these items within the text.

For example:

Figure 1. Map of languages in Papua New Guinea
Alt text: This map shows ...
Long description: ...

For authors that cannot provide the alt text/long description materials within the manuscript file itself, please supply a separate text file that clearly identifies each item that requires this material.

For example:

Chapter 1, Figure 1:
Alt text: ...

If we do not receive or are unable to locate alt text for any images that appear within a publication, this will be requested during the proofing process to ensure that your work is compliant upon publication.