Some interesting facts about NVIDIA’s newly open-sourced Image Scaling technology have come to light. According to users on the Phoronix forums, unlike AMD’s FSR spatial upscaler, NVIDIA’s NIS is a D3D compute shader (FSR is a generic HLSL/GLSL shader compatible with any API and hardware) limited to DX11+ compatible games and systems. Furthermore, NIS is much more abstract and high-level compared to FSR which makes it hard to customize and tweak depending upon the game.
NVIDIA’s Image Upscaler also appears to be a simple single-pass shader wherein upscaling and sharpening are both done within the same pass. AMD’s FSR, on the other hand, uses separate passes for each, making it a more intricate shader. The fact that NIS isn’t portable to Vulkan or OpenGL means that it can’t be used on titles using any other API other than DX11+, rendering it useless for Linux and non-Windows platforms. In the end, NIS appears to be a PR stunt more than anything else, trying to undermine AMD’s promise that FSR will run on “just about any PC”.