http://www.pure-newshome.com/shuhei-...ardware-based/
Yoshida, President of Worldwide Studios has confirmed that the game upscaler of the Playstation 4 is indeed Hardware based.
He confirmed this via a question on twitter
But let’s get some things clear here. What’s the upscaler for? Well there’s some games that might be native 720 or 900 and automatically gets upscaled to 1080p, but this is only for games that aren’t 1080p native, it can also be used for upscaling to 4k resolution.