Yuan Fu likes to take notes in which he can embed images. You can do that with Org, of course, but Fu doesn’t like that Org’s solution boils down to a link to a file. That means you have to keep the file paths in sync. He wanted a solution that embedded the image in the file and made it easy to resize the image on the fly.
To a first approximation, his solution is simple: Embed the image as a Base64 string at the bottom of the buffer and put an internal link to it at the point to where it is to appear. Of course, there are complications. First, there’s handling the resizing. That’s not too hard but there are also display issues such as having reasonable scrolling. Fu has some animated screenshots that show this in action. It appears to work well.
The code does not appear to be in Melpa and Fu doesn’t say whether he plans to submit it but it’s a single file and should be easy to load and try out. If you have a need to permanently embed images in a file and don’t want to have to worry about keeping file paths in sync, this is a good solution.