https://wccftech.com/amd-fsr-based-on-modified-lanczos-upscaler-enabled-on-nvidia-gpus-using-control-panel-in-all-games/

AMD's FSR has received a positive response across the gaming and tech community for bringing an open-source solution that rivals NVIDIA and is hardware agnostic (in a way). AMD FSR runs on both, NVIDIA GeForce and AMD Radeon GPUs and several developers have shown just how easy it is to implement within games though it looks like people digging through the source code have found out that the tech behind FSR might be a little too similar to something that NVIDIA has offered in its control panel for a while now.

As discovered by Alexander Battaglia of Digital Foundry, the AMD FSR (FidelityFX Super Resolution) technology is based on the Lanczos upscale, albeit, a modified version of it. The FSR algorithm is actually composed of two main passes, EASU (Edge-Adaptive Spatial Upsampling) and RCAS (Robust Contrast-Adaptive Sharpening). The EASU pass provides spatial only scaling at a relatively low cost & which makes it appropriate for lower-end GPUs on desktops and laptops.