Everyone wants extra performance from their PC hardware, right? And that’s where technologies like AMD’s FidelityFX Super Resolution (FSR), Nvidia’s DLSS and Intel’s upcoming XeSS are all about – essentially allowing the GPU to render at a lower resolution, then either upscaling or reconstructing to the native output of the display. In a sense, this is new territory for PC, where native resolution rendering was for a long time considered the only way forward. However, in console land, ‘smart upscaling’ isn’t new, really coming to the fore with the launch of PS4 Pro in 2016. PC has embraced similar techniques, but has also spawned its own blend – and AMD’s FSR in particular stands apart. So when Team Red asked us if were interested to talk FSR, we jumped at the chance. AMD’s approach is different, both in terms of technology and philosophy.
To set the scene, what we’ve traditionally defined as ‘smart upscalers’ have all had one thing in common: the use of prior frames as a reference for improving the quality of the next one to render. All of the effort the GPU has spent in generating a previous image, working in combination with motion vectors that inform the game of where those pixels will end up in the future, allows for extra detail to be injected into a freshly rendered frame. The two key technologies to use this initially were checkerboard rendering and temporal super-sampling. These techniques what made PS4 Pro’s 4.2TF GPU capable of producing a pretty convincing 4K output and they’ve been used on all consoles by this point. Similar techniques are now found in a range of engines supported on PC too – and with an added component from machine learning, that’s how DLSS 2.x works as well, and additionally, it’s how we expect Intel’s XeSS to play out.
When AMD revealed that FSR would be a spatial-only upscaling solution, we were sceptical, because rather than drawing on data from prior generated frames to increase detail, it has no visibility on data from anything other than the current frame which inevitably leads to temporal discontinuities. AMD was effectively pursuing techniques that the industry in general had basically left behind – FSR isn’t a reconstruction technology like TSSAA or checkerboarding, rather an upscaling one. However, there is more to it than upscaling alone: it is augmented with the ability to detect and refine edges and to mitigate the aliasing artefacts that would otherwise result – and that’s what makes it intriguing. Then there is the philosophical angle too. Nvidia DLSS is closed source – a black box for developers, if you like, and only capable of running on ML-equipped cards. Intel XeSS aims to be more open but certainly to begin with, there’s no source access.
AMD’s FSR is the direct opposite: the source code is fully open and as it’s a fully software-driven technique and it should run just fine on any modern GPU, whether it’s sitting in a PC or a console. This has led to a wide range of support arriving very quickly, with unexpected ‘homebrew’ support added to various emulators, and even implementation in brand-new console games, such as Myst and (we suspect!) Arkane Studios’ Deathloop.