Normal upscaling is picking pixel values in the higher-resolution target image that when run through an equivalent downscaling function would fit the smaller im

Normal upscaling is picking pixel values in the higher-resolution target image that when run through an equivalent downscaling function would fit the smaller image. There are lots of degrees of freedom to make things up. Then there is undoing reversible transforms, such as some blurs. That makes information that was there all along more legible. Such as the example you have there. This paper is a case of both. It does upscaling, but it uses temporal information to find additional constraints that can be used to restrict the degrees of freedom of the "making values up" part. So it's part information recovery, part hallucination.