Upscaling image with SD3.5 Large up to a size of more than 1 megapixel.
We'll use imgtoimg, this controlnet Blur: https://civarchive.com/models/984199?modelVersionId=1103617
And this extension (Tiled Diffusion)
With the help of tile splitting, you can overcome the limitations of SD 3.5 in 1 Megapixel.
There is recommendation: tiling the image at a tile size between 128 and 512. But i got better result with preset parameters of node, and other parameters took from post of aeroumbria на одном ресурсе.
You can try different parameters and achieve much better results, it takes me a very long time to do this because of the old CPU and 8GB of VRAM. You can use any model based on SD 3.5 Large. I also tried Absynth - SD3.5L and SD3.5-SLG-Weighted-Merge GGUF version.
You can also inpaint without upscale, it turns out beautifully.
The images that are submitted for imgtoimg and for the controlnet input must be the same size. To use controlnet, you need the latest version of ComfyUI. If you get an error, update ComfyUI.