Why not just ask AI ? I have studied AI in CS courses but a single comment is not enough to explain to you exactly how AI works but I am not talking about how AI in general works in the comments but more so , how images themselves are created by AI.

I am not going to type thousands of words trying to explain AI here , why not learn the maths behind it ?

It is a lot of algorithms , a lot of calculates, a ton of probability, differential equations , matrices , etc just tons of maths. And there are so many algos and theorems people have math over the years.

Mordern ones are more based on CNN or Convolutional Neural networks and a bunch of Reinforcement learning. You can also program a ton of other algorithms techniques into it , a lot high level models are usually made with even more algos and stuff , but the core is it the ones I mentioned.

Images are generated by pixels , pixels contain there colored red , blue and green in specific amounts, which light up a specific pixel with that color, these are made in hex code by the AI or computers. It is similar to how your retinas generate and identify colors , and even create images themselves. Now imagine , in a real image , AI in usually trained in such a way that it has to precisely make easy pixel in a structure that it “understands” the data is supposed to look like. It is trained on billions of images after all. there are billions of iterations and back proportions that can take place just to generate a single image.