VQGAN does the generation work, CLIP just says if it's good not, improve the latents, repeat. Here's a good technical writeup: https://ljvmiranda921.github.io/notebook/2021/08/08/clip-vqg...
And of course, the most-common VQGAN was trained on ImageNet, which likely doesn't have every movie poster as training data. (it could be in CLIP though)
> a brief text description of a movie
However apart from the existence of a golden ticket, I wouldn’t expect those details to make it into a brief description of the film. And yet there’s an original poster matching those details that the VQGAN + CLIP generated image seems to draw from.
That's not enough for reconstructing the face of John Malkovich from text, you need minute facial feature parameters (eye shape, nose shape, eye-nose distances etc etc)
Star Wars is an interesting example because it appears to include elements lofted directly from the film (bits of stormtroopers body) alongside a princess who definitely isn't Leia. The algorithm might be creating things from scratch at a high level, but the constituent elements are pretty clearly close reproductions of parts of the source material
The interesting thing to do, I think, would be to have data set of general images, and use a movie description to pull from those images.
Unless the descriptions were particularly detailed, I would expect that a lot of this comes from the training data and the descriptions are just prompts for the model to recall which film it is.
For instance, Willy Wonka & the Chocolate Factory (1971) is clearly based on this real poster:
https://www.amazon.com/-/es/Póster-Online-Willy-Chocolate-Fa...
This seems less “generate a poster from a description” and more “recall half-memorised posters“.