I want to be able to enable (or even better enable and disable at will) image previews (thumbnails) in Pantheon Files.
In dconf Editor in org-gnome-desktop-thumbnailers nothing is desabled.
PCManFM and Thunar both have them.
sudo scratch-text-editor /etc/xdg/tumbler/tumbler.rc
At the line # Jpeg thumbnailer, set Disabled=false
or Disabled=true
to enable or disable jpeg thumbnails.
To enable for png and other image formats, under the line # PixbufThumbnailer in the same file, set Disabled=false
.
If tumbler is enabled then you should get thumbnails when viewing local folders (try pressing refresh if not - if still not then try restarting the tumblerd process using gnome-system-monitor or the commandline).
There is a dconf setting that turns on thumbnailing of remote folders. If you have a recent version then right clicking on a remote folder background should give you a option to turn this on or off.