More at the link:

Question: This is being marketed as a 4K console for 4K gaming. How are you approaching that as far as the resolution you’re rendering at?

Hermen Hulst: The big thing about the Pro is it can handle 4K and HDR. First, I can tell you that it’s massive in terms of the visual difference, but it’s not massively different in how we make games. Our games have been running HDR since Killzone 3. But only now do we have displays that can actually show that. A lot of our assets are already prepared, future-proofed to be able to handle very high resolutions, but only now do we have displays that can show that as well. A lot of the content in the game is identical. It’s just shown now on these very high-end displays.

Question: Are you talking about the exact rendering resolution at this point? Are you rendering in 4K?

Hulst: There’s a lot of magic happening. It’s all very complicated and Mark Cerny has a fantastic seminar planned in a couple of weeks where he goes into the nitty-gritty of it. It’s not native 4K, but as you’ve seen for yourself on the screens, it’s acceptably so. It’s close enough that you can see the difference with normal human eyes.

Question: Is it safe to say that it will be easy to have a game that works on both the new model and the previous model?

Hulst: Yes. It’s not like we have separate teams working on different versions. We have maybe one or two technicians looking at the specifics of the hardware, but everybody’s making the game. Obviously somebody like JB, as an art director, will specifically look at how we can optimize for HDR, how the image can truly stand out in 4K. But it isn’t something that’s going to split off a second team.

Question: Can you talk about specific things that may look better with the game running on a Pro, but on a 1080p TV?
Hulst: You’re always making tradeoffs as far as image quality versus performance. With a Pro, we don’t necessarily need to do that anymore. We can have the image quality and the performance without making the subtle tradeoffs – things that most people might never notice, but that we’re very attuned to. That may be one of the areas where—what it’ll do is render the game at 4K, and then use a technique called super-sampling to send it to a 1080p screen. It’s similar to how renders get done for movies, where it’s rendered at a very high sample rate and then sent to a normal screen. It’ll be a much more stable, much more aesthetically pleasing image from a technical point of view.

Question: With super-sampling, does that mean aliased edges will look better?

Hulst: Jagged edges won’t exist. Any graininess will be removed. It’ll be a much crisper image. The resolution will be very even. And the framerate will be positively impacted.

We can automatically detect what your display is. We want to make it very accessible. We don’t want to have to give you a lot of options as far as what filtering techniques to use and so on, like you see on PCs. We know exactly what the hardware can do and what display you have. If you have a 4K screen, we’ll know that and we’ll optimize for it. If you have a 1080p screen, which many people will still have, we’ll optimize for that experience as well. There aren’t any negatives for the vast majority of players who are still on 1080p. They’ll have a very solid 1080p experience.

Question: Can you talk about temporal and spatial AA in a way a non-tech person could understand?
Hulst: Wow. On a very simple level, spatial AA is if you look at a static image and see jaggies, temporal AA is if you look at a moving image and see shimmer. That’s the two things the Pro will be specifically good at combating.

http://venturebeat.com/2016/09/18/drilling-down-into-ps4-pros-4k-graphics-on-horizon-zero-dawn/