[O] Embedding and extracting license/author information in an image file

[Julien Cubizolles]

I often include images in my org documents and would like to properly
cite the license, and/or author. I was thinking that this could be
simplified by:

* embedding the license/author information in some metadata of the jpg
  or png file (it seems that some standard called xmp can be used to
  embed data in png/jpg [fn:1]) preferably using some emacs tool

* getting org to add a footnote with this information when linking to a
  file with this kind of information.

Could it be done ? Do you know of an emacs package providing read/write
access to this metadata ?

Footnotes:

[fn:1] https://en.wikipedia.org/wiki/Extensible_Metadata_Platform