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AMD FidelityFX Super Resolution vs Vanilla Upscaling + LumaSharpen: Is FSR Better than Traditional Spatial Upscaling Techniques?

Right before AMD unveiled its FidelityFX Super Resolution, NVIDIA held a press briefing with an aim to distinguish its much marketed DLSS upsampling technique from existing methods. Of course, it wasn’t said outright, it was heavily implied that the company was comparing it to AMD’s upcoming solution. AMD had already announced earlier that its Super Resolution technology would be a spatial upscaling technique without the need for data from the previous frame (jitter offsets or motion vectors), and NVIDIA used this to essentially brand it as an upscaling-sharpening pass:

AMD, later on, revealed that FSR was more than just a simple spatial upscaler. It combines EASU (Edge-Adaptive Spatial Upsampling) with a CAS (Contrast-Adaptive Sharpening) pass to try and get back some of the lost detail. More details below:

  • An upscaling pass called EASU (Edge-Adaptive Spatial Upsampling) also performs edge reconstruction. In this pass, the input frame is analyzed and the main part of the algorithm detects gradient reversals – essentially looking at how neighboring gradients differ – from a set of input pixels. The intensity of the gradient reversals defines the weights to apply to the reconstructed pixels at display resolution.
  • A sharpening pass called RCAS (Robust Contrast-Adaptive Sharpening) extracts pixel detail in the upscaled image.

This definition alone should tell you that FSR is more advanced than traditional bilinear and bicubic upscaling techniques. However, since no one (that I know of) looked at this in detail, I decided to do some testing and see if FSR is actually better than bilinear or bicubic upscaling. For this round of testing, I primarily stuck to Terminator Resistance simply because it allows for comparisons and benchmarks more easily than the other titles featuring Super Resolution.

Test Methodology and Terminology

The testing was conducted at 4K using a GeForce RTX 3070 and a Core i7-10700 processor (sorry, don’t have access to a Ryzen|Radeon PC this week). The ultra-quality and quality preset of FSR were compared to native 4K with an internal resolution of 75% and 65%, respectively. These correspond to the input resolution that FSR takes in at these presets and then upscales them. We combined the latter with a ReShade LumaSharpen shader to make sure that the results are solely distinguished by the quality of the Edge-Adaptive Spatial Upsampler:

It’s hard to tell the four apart unless you’ve got a large 4K screen, so here’s a close-up:

75% Internal Res+LSharpen vs FSR Ultra Quality

The differences are subtle but FSR UQ does a much better job at getting rid of the jaggies, and also retains more detail than a simple upscaling+sharpen pass. This is because FSR’s spatial upscaler works to remove jagged edges and retain thin objects/lines in the process. You can see this quite easily in the middle portion of the shot with the Y-shaped twigs. Overall though, LumaSharpen produces a sharper image at the cost of increased aliasing.

Once again, as you can see, FSR is superior at anti-aliasing the cable than a simple upscaling plus sharpen filter:

75% Upscale + Sharpen vs FSR UQ

It’s quite remarkable how a simple sharpening pass does wonders for image quality. ReShade shaders have sure come a long way since the days of SweetFX:

In the below (magnified) shot, you can see how FSR removes the jaggies that remain with a simple upscale-sharpen pass (note the dustbin, steel fence, and the two cables). One thing is clear. FSR is much better at removing aliasing than all existing spatial upscaling techniques.

75% Upscale + Sharpen vs FSR UQ

You can find the original full-screen shots here.

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Areej

Computer Engineering dropout (3 years), writer, journalist, and amateur poet. I started my first technology blog, Techquila while in college to address my hardware passion. Although largely successful, it was a classic example of too many people trying out multiple different things but getting nothing done. Left in late 2019 and been working on Hardware Times ever since.

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