Confused about AMD's FSR Redstone update? You're not alone – here's what it all means for PC gamers

Upscaling, faster frame rates, rays and radiance explained

· TechRadar

Features By Darren Allan published 14 December 2025

(Image credit: Friends Stock / Shutterstock)

AMD's FSR Redstone update was finally launched earlier this week – roll out the rendered red carpet – and it arrived boasting four separate pieces of tech.

Well, I say these four features have arrived, but they haven't – or one of them hasn't, rather, and it seems a long way off – plus one of them is actually here already, and isn't new at all.

Confused? Well, it all feels a bit murky, messy, or even chaotic, which is surprising given how long PC gamers have been keenly awaiting Redstone as AMD's effort to catch up with Nvidia DLSS 4 (which has been out for almost a year now). You'd have thought Team Red would've had time to craft and hone its launch material and marketing message for Redstone, but that doesn't seem to be the case.

On the face of it, the four pieces of tech that comprise FSR Redstone are as follows:

  • FSR Upscaling
  • FSR Frame Generation
  • FSR Ray Regeneration
  • FSR Radiance Caching

If you thought AMD already had frame generation in FSR, and so you're confused about what FSR Frame Generation is, or if you thought FSR 4 was upscaling, and you're scratching your head about what FSR Upscaling is – is it FSR 4, FSR 4.1, or a new version entirely? – then I totally get where you're coming from.

AMD has not done a very good job of making some of this clear, so I'm going to step in and offer my take. I'm going to go through these four features, one by one, and define what they really are and whether they've actually arrived or are still waiting in the wings (cough, Radiance Caching, cough).

(Image credit: AMD)

FSR Upscaling

Upscaling, for the uninitiated, takes a lower-resolution frame and scales it to a higher resolution, delivering near-native quality while running faster and more smoothly. As AMD officially bills this, FSR Upscaling was "formerly AMD FidelityFX Super Resolution 4," otherwise known as FSR 4.

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