Cervage Hi Cervage, as the release note explains, if all of the images in the /userfiles/images/ directory on the app server were moved to the database, then the current source of the background image should also be in the database (USERFILES table).
However, if you don't have access to the database, then I suggest contacting your TRIRIGA implementation team. But if that team no longer exists, then I suggest contacting IBM Support for more detailed "how to" instructions. Good luck!
Copying @jeff_long and @such .