Topaz Labs has a bunch of Photo/video AI software that lets you upscale from some pretty shitty source images.
I used it at work to convert a 640x480 image to 4000x3000 effortlessly.
Much better than just blowing it up in paint/photoshop which does nothing.
New detail is literally generated using AI.
There are other tools like AI background determination etc for green-screening without a greenscreen.
There are free trials (30 days) if you want to try it out.
EDIT: another 15% off with BLACKFRIDAY15
hmmm this is pretty tempting, I've been using the gigapixel trial for a while but might purchase it with this deal. Thanks!
Edit: hmm seems like you have to buy everything rather than just the individual programs :(