Hi Gero, thanks for your post and work! I shall look into how we can make Jalbum's RSS feed better and more compatible as a default. We might change just when an RSS feed is generated from album build time to publish time. Then Jalbum would know the destination URL and could produce absolute links right away.
in the "Collect item details" section, I modified "ri.guid = entityEncode(getFolder() + "/" + imagePath)" in "ri.guid = entityEncode(getFolderUrl() + "/" + imagePath)"
changed the pubDate for the one originally used by Jalbum, because the format date was wrong, probably as I'm French, the date was starting with "dim., 07" instead of "Sun, 07", don't know why. As I'm not technical at all, I preferred to change it to the genuine variable.
added personal information on my website (author, copyright, etc.)
Attached is my album.rss file, if interessed. I validated it with the Feed Validator and it is now a valid RSS feed.