If you had a blog with images, and you include images as relative links, just the filename for example, no domain, nothing, that is to say a perfectly valid URL, and everything looks as expected, what would you expect the feed to contain? My naive idea is that I can send the same HTML to the feed and it is up to the feed reader software to resolve relative links relative to the original URL of the blog post (which is hopefully part of the feed). One thing is for sure, though: the images of the blog post cannot be rendered as-is since the links won't work without some extra effort. From my perspective, it would be just as valid to just render the blog post without the images. I guess I'm curious about your expectations.

My own feed reader reduces every feed item to a small extract of uniform size with no images. If the extract catches my interest I will click through and read the actual blog post on the remote site.