Accessibility specialists in the Ministry of Justice (MoJ) have cautioned government colleagues against the use of AI in writing alternative text for images on their websites.
Katherine Moonan and Samantha Merrett have outlined the position in a Civil Service accessibility blogpost on writing alt text, which is used to described images for people who are not fully sighted.
They said an AI system can use image recognition to write a description and can save time in what can be a lengthy process when there a lot of images on a site. But it often provides a very literal description that lacks context and can prove misleading.
An experiment with an online alt text generator produced four results, three of which were not sufficiently accurate, while the fourth was incorrect and of no use.
Clarity and consistency
“As this experiment shows, human descriptions are more accurate. We are able to describe images using clear and consistent language and take into account the surrounding context,” Moonan and Merrett said.
“You may choose to use automatically generated descriptions to draft alt text and then you can manually check that they are correct and appropriate before you publish.”
They suggested an alt text decision tree can help in writing better text, and pointed to guidance from the Government Digital Service suggesting the alt text box in a publishing system is left empty and a description of the image is written in the body text instead.
