As far as I understand it, the Neural Style Transfer uses a content image and a style image, and generate a new image based on the two images.
It tries to find a set of pixel values such that the cost function
J(C, S) is minimized. It does not have any labels associated in advance, but it has an output (generated image) that should be the target of the learning.
However, I'm not sure if this is considered supervised or unsupervised learning. Which does it belong to?