NVIDIA DLSS 2.5.1 version debuted in the latest Portal RTX patch released last week. Following the festivities, it has now been found that this latest version of the software doesn't feature any built-in sharpening filter anymore. Advanced users had been using alternative methods (like hex edits or the DLSS SDK .dll, which, however, added a watermark) to fix the oversharpening issues in select games, like Red Dead Redemption 2 or God of War. The problems were most noticeable during motion.

　　The news was confirmed by NVIDIA's RTX Unreal Engine Evangelist Richard Cowgill (fatheadlifter on Reddit) with the following messages. NVIDIA is apparently recommending that game developers use NVIDIA Image Scaling sharpening going forward.

　　Yeah, DLSS sharpening is now deprecated in NVIDIA DLSS 2.5.1. We’re recommending devs use NIS (Nvidia image scaler) sharpening instead. NIS has an arguably superior sharpening technique and can also provide a cross-platform, non-RTX hardware fallback for upscaling.

　　The latest DLSS simply doesn’t use the old DLSS sharpening method anymore. We’re recommending to devs they use NIS sharpening instead when implementing DLSS. This should result in better image quality.

　　NVIDIA Image Scaling (NIS) was released in November 2021 as an upgrade to the previous image scaling technology. The new algorithm uses a 6-tap filter with 4 directional scaling and adaptive sharpening filters. Scaling and sharpening also happen in a single pass, boosting performance.

　　NVIDIA Image Scaling works with GPUs from all vendors (including AMD and Intel) and is open source. Game developers interested in adding NIS to their games can download the latest SDK version from GitHub.

　　If you're interested in checking out the unsharpened upscaling results available with NVIDIA DLSS 2.5.1, you'll have to either download the latest .dll from TechPowerUp and manually inject the file in the game of your choosing or use the handy DLSS Swapper tool from Australian coder Brad Moore.