How AMD FidelityFX Super Resolution Works
The name FidelityFX has been around for a while, it's a combination of various turnkey game effects and image quality enhancements given to game developers under AMD's GPUOpen initiative. FidelityFX Super Sampling, the subject of this review, is a feature that lets you significantly improve the performance of your game at minimal cost to visual quality.
Your game is rendered at a resolution lower than your display resolution, and the resulting image is processed through an upscaling algorithm that attempts to reconstruct details.
FidelityFX Super Sampling (FSR) is integrated into the game as a shader-based post-processing code. It's agnostic to the hardware beyond programmable shaders and can thus run even on NVIDIA hardware. Within the game engine's rendering path, FSR sits between a tone-mapped anti-aliased output of the lower-resolution render and post-FX that can introduce visual noise, such as filmgrain. Only the 3D graphics are processed, the HUD is overlaid later, so it's always rendered at the native resolution. The FidelityFX Super Sampling upscaler operates in two passes. One is an upscaling pass, which uses a spatial upscaling algorithm that detects the edges in the image and sharpens them, while attempting to preserve details, and the other is a sharpening pass, which "adds" crispness to textures to improve image quality.
This is a completely different approach than NVIDIA DLSS 2.0, which looks at multiple images in a sequence, so it has additional pixel information. NVIDIA DLSS also requires game developers to provide them with motion vectors to avoid rendering errors due to this temporal appraoch. FSR is much simpler and requires no engine integration (other than the FSR shader render pass).
At what resolution your game is actually rendered is decided by the FSR quality preset you choose in your game's settings.
The various quality presets alter the render resolution, and hence impact resolution. With each step, you trade image quality for performance. The table above lists the various render resolutions for target display resolutions based on the quality presets. Since the scale factor changes with each preset, the performance gained between the native resolution and highest performance setting can be drastic.
Since FSR is essentially a drop-in render stage, practically any game can integrate it, and any current-generation hardware can run it. AMD is hence working to integrate it with as many game engines and games already launched or in development as possible. While Epic Games / Unreal Engine is not listed here, we have tested Unreal Engine based titles today, and FSR work perfectly fine in them.