Hi I tried here first with the problems i had with art mode for the frame.
I phoned Samsung after 15 minutes having explained the issues that I have with uploaded pictures having only 1 border choice I then got cut off. I waited patiently 15 minutes as the lady had my mobile no. to ring back.
annoyingly I had to phone back go through all the security questions again. But this time the lady understood the problem checked my tv remotely for any issues to which there were none. So now to the important part .
Size of pictures not just 16.9 but the resolution needs to be 3840 x 2160
I use a free program called fastone which does batch editing to resize to required resolution