If you're purchasing a retail copy of Call of Duty: Ghosts for PlayStation 4 and intend on playing through the game in native 1080p, you're going to have to download a patch.
There's apparently a "configuration issue" in the single-player that requires an update in order to remedy the problem. If you don't download the patch, you'll be playing through the campaign in 720p upscaled to 1080p.
"Call of Duty: Ghosts runs natively at 1080p on the PlayStation 4. There was a configuration issue in the retail version on single player mode only," Activision explained to Joystiq. "This has been addressed with a day one software update. People will be able to download the day one update when PlayStation 4 launches in their territory and play at native 1080p."
So there you have it, future PlayStation 4 owners. Don't forget to download the patch.