We have about one gigabyte sized collection of family photos. For each photo we would like to specify rotation angle (90 DEGREES or -90 DEGREES) and a one-line comment.
There are individual image viewers like Viewnior and Eye of Gnome, but I think they do not have a field for comments. There is KPhotoViewer, KODI (xmbc), but I haven't seen a field for comments there, either. For either of them I do not know how they implement rotation, via metadata or by modifying the bytes within the image area.
I am looking for a free software (libre, not necessarily gratis) solution that works on Debian GNU/Linux.