>>7593348gigapixel is probably the most useful software for improving images to use them as a wallpaper
has a pretty good chance of improving an image overall if not completely, especially if you spend time messing with different levels to scale it at and adjusting the noise and blur suppression sliders
this was actually scaled at a "1x" rate but somehow still made it sharper and increased resolution
the 2x and above settings cause more artifacting for things that are too low res or out of focus, and can result in twisted nightmare faces or make things look surreal like an oil painting, but often work pretty well.
so if you have issues just set it to 1x after clicking save image and it should still make it considerably more detailed like this
for whatever reason it says its scaled at 2x but the 2x setting in the software looked way worse than the 1x i set it at