ActivityPub: Image mapping

[mediaformat]

Issue description

Id like to get an idea of how the image post type is used.

Specifically, is the Description field commonly used in any way that overlaps or is compatible with the image alt attribute?

Why is this important?

The (ActivityPub) Fediverse has a strong tradition of providing descriptions of images.

Who does this affect?

Vision impaired users, or users of screen-reading technology.

Can we use Descriptions as alt text?

The Description field is a rich text field, for this to work as alt text tags would need to be stripped.

Alternative approaches

• Provide separate plain text fields per image

#3186

[mediaformat]

Simply mapping the image description to the an image alt text works if there is only 1 image, when multiple images are used... all images will have the same alt text, which is less than ideal.