but the table exists outside the alt text, right? i don't know a mechanism to say "this html table represents the contents of this image" , in a way that screen readers and other accessibility technologies take advantage of
The figure tag has both image and caption tags that link them. As far as I remember, some content could be marked as screen reader only if you don't want for the table to be visible to the rest of the users.
Additionally, recently I've been a participant in accessibility studies where charts, diagrams and the like have been structured to be easier to explore with a sr. Those needed js to work and some of them looked custom, but they are also an alternative way to layer data.
The figure tag has both image and caption tags that link them. As far as I remember, some content could be marked as screen reader only if you don't want for the table to be visible to the rest of the users.
Additionally, recently I've been a participant in accessibility studies where charts, diagrams and the like have been structured to be easier to explore with a sr. Those needed js to work and some of them looked custom, but they are also an alternative way to layer data.