I can share a few other tips about techniques I use to get a great result. I typically will upscale the photo before uploading it to the sites I mentioned in my previous post above. I may even go into Photoshop and use the Blur or Smudge tool on noisy and grainy areas when I try to upscale. I use Topaz Photo AI to upscale and almost always leave it on the Autopilot settings. Still, I will experiment with switching between Low Resolution, Standard, and High Fidelity on the upscale options to see which option produces the best result.
After the image is generated I may use the Blur, Smudge, and Clone stamp Photoshop tools to move things around or smooth out weird results. Also the remove tool. Then I might even upscale again, especially if I forgot to upscale it before I uploaded it to the Nudify sites. If the end images look too smooth and unnatural you can use the Filters in Photoshop to add noise and grain back to the final image. There are free tools online and free trials to emulate some of the same techniques that Topaz Photo AI and Photoshop use if you research.