There are two worlds; the old good one Proteus OR Starlight Mini & Sharp. So Proteus is solid but the image improvements are not spectacular. The new stable diffusion based ones are high reconstruction models, could be promematic based on content but when you have license for local use (and the gpu hardware), you must try it.
Workflow to try
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Bring your source to 540p vertical lines using simple Lanczos, NTSC 480 → 540 for PAL 576 → 540. You can use hybrid, Virtualdub or something else. Here you can also crop a little bit when needed.
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Model Starlight Mini 2x Upscale 540 to 1080
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Reimport result into Topaz, choose model “Starlight Sharp” and do 1x no upscale. When you do 1080, Starlight Sharp does not use built in NYX-XL and the result is much more natural. Both SLS and SLM does some denoise, by how the model works.
