The 2020 fan upscale projects utilized "Generative Adversarial Networks" (GANs). Unlike standard upscaling, which just stretches the image, AI upscaling predicts what missing pixels should look like based on patterns it learned from millions of high-resolution images.
The 2020 AI upscale of DS9 is a triumph of fan dedication. It proves that with modern technology, studios have little excuse for letting legacy content rot in Standard Definition. While it isn't a true Blu-ray replacement, it is the closest we will likely get to seeing the Dominion War in 4K. star trek deep space 9 s01 ai upscale 4k 2020
To understand the value of this upscale, you have to understand the source material. which just stretches the image
What "AI upscale 4K" means for DS9 S01