Ultimate SD Upscale extension for AUTOMATIC1111 Stable Diffusion web UI
Now you have the opportunity to use a large denoise (0.3-0.5) and not spawn many artifacts. Works on any video card, since you can use a 512x512 tile size and the image will converge.
News channel: https://t.me/usdunews
All instructions can be found on the project's wiki.
More on wiki page