I wonder why the option "Images used by your current configuration" is grayed out when I do use some custom images for labels? Is there a special folder where Opus expects me to hold all custom images (I use /home/Images/)?
But it seems to me that Opus is making the smaller images of whatever I point it to and cache them somewhere...
That option only applies to images configured in Preferences / Display / Images.
I see... Would it be too hard to include label images as well? 
Put them in /dopusdata/User Data if you want them to be included in backups.
Oooops, this is on C: that I consider temporary drive. I keep all my important installations on separate partition 
, but since you say it will be included in the backup I shall do as you say.
I see I may edit manually colorgroups.oxc in order to avoid reselecting all images manually. 
You can create a symlink (pointing to \Roaming\GP...) and keep your DO-config on another drive