I ran across an answer today that looked like it could use a little help with accessibility (WBT's answer to Train Station vs. Railway Station). Specifically, there is a link to "here" that would be better attached to something more descriptive; I thought while I was at it, I'd check to see if it needed image descriptions for the Google Ngrams that make up the bulk of the answer.
In fact, the images do not include any alternate text. However, they also apparently were not added via the Image button, because the code does not include the usual placeholder for such text. Instead, there is just this:
I'd still like to add alt text, but I'm not at all code-savvy, and I don't want to disturb the current coding for fear it will make the image go away. Should I copy the source address, add a duplicate picture (with description), then delete the original? Is there a more elegant approach?