AMD's FidelityFX Super Resolution (FSR) uses temporal upscaling to produce high-resolution images from low-resolution input. Instead of rendering at native resolution, your application renders at a lower resolution, then uses FSR to upscale the initial render results to native resolution, making it possible to use otherwise costly rendering processes on limited hardware.
Unreal Engine (UE) supports a mobile-optimized version of FSR 1.0. This page provides instructions on how to enable Mobile FSR as well as a reference guide for its configuration parameters.
For more technical details and guidance for using FSR, refer to [AMD's documentation on FSR 1.0](https://github.com/GPUOpen-Effects/FidelityFX-FSR](https://github.com/GPUOpen-Effects/FidelityFX-FSR).
Benefits of Mobile FSR
This implementation of FSR slightly reduces render quality, but produces a performance boost between 2x (using full precision) and 4x (using half-precision). This performance improvement is so large compared with the quality tradeoff that we advise using Mobile FSR unless your application's final render isn't the full size of your screen.
Enable Mobile FSR
To enable Mobile FSR, follow these steps:
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Open the Plugins window and enable the Mobile FSR plugin, which you can find in the Rendering category.
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Set the CVar
r.Mobile.FSR.enabledto 1. You can do this in the console or in your Device Profiles.
Once you enable Mobile FSR, the variables for configuring it become available. The variables r.Mobile.FSR.RCAS.enabled and r.Mobile.FSR.Upsampling.enabled are both set to 1 (true) by default.
Mobile FSR will take effect in the Mobile Preview in Unreal Editor.
Configure Mobile FSR
You can configure Mobile FSR using the following parameters in your Device Profiles or console:
| Parameter | Description |
|---|---|
r.Mobile.FSR.enabled |
Enables Mobile FSR support. |
r.Mobile.FSR.RCAS.enabled |
Enables the sharpening (CAS) part of FSR, which provides the most benefit to image quality. |
r.Mobile.FSR.RCAS.Sharpness |
Controls the level of sharpness generated by CAS. 0 is the sharpest setting, while higher values will reduce sharpness. |
r.Mobile.FSR.RCAS.Denoise |
Enables support for grainy input such as dithered images or input with custom film grain effects applied prior to FSR. Useful for stylized games or portions of games with effects enabled. |
r.Mobile.FSR.Upsampling.enabled |
Enables the upsampling portion of FSR. You are not required to enable upsampling with CAS, but it can provide some benefit to quality. |
r.Mobile.FSR.DisableCompute |
Disables compute passes for FSR, which can improve performance on Mali devices. |
Limitations
Mobile FSR should work as intended with most post-processes, but may produce unexpected artifacts if you apply intentional noise or patterns as part of a post-process.
Further Reading
Refer to [AMD's documentation on FSR 1.0](https://github.com/GPUOpen-Effects/FidelityFX-FSR](https://github.com/GPUOpen-Effects/FidelityFX-FSR)for technical details guidance for using FSR in your applications.