want a file format easily edited and read by emacs that allows (multiple) pictures to be included

[Dan Hitt]

For the notes i keep, sometimes i would like to sometimes include a
picture (jpg or png or maybe some other format).

emacs seems to have no problem displaying a picture but i would like
to add words to it.

So reading the file in emacs would be something like looking at html,
but i would prefer it something to be hot-editable, just like text
files are.

That is, i would prefer not to have any markup in the file whatsoever,
just a block of text, then a picture, then more text, then another
picture, and so on.  Perhaps an unprintable character could divide the
sections, and each section type could be recognized as either starting
with the magic words of a jpg or png and be presented as a picture, or
otherwise, presented as utf-8.  (So i guess the unprintable character
would be markup, but certainly i wouldn't want something as lengthy as
<img> to appear in the file.)

Ideally, emacs would recognize the type of file it was by a
mode-defining like at the top, like -*- text -*- (except, of course,
not text).

Does any file format/mode combo like this exist?

TIA for any clues!! :)

dan