gthumb currently relies on gdk-pixbuf to save images. tiff save support was only added to gdk-pixbuf as of 2006-02-28 (http://svn.gnome.org/viewcvs/gtk%2B?view=rev&revision=14847). It should work if you have an up-to-date distro.
gdk-pixbuf does not have tga or gif save support at all. It's not a bug; it's just not implemented :-( - Mike -- Rotating Images couldn't be Completed for some format https://launchpad.net/bugs/55594 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
