Content for neural network training

Can someone tell me if using copyrighted content for neural network training is infringement or a fair use? For example: Someone took 100000 superhero pictures from Google for training. After this neural network can create superhero pictures with the query of user. Is it an infringement or a fair use? Can developer sell these created pictures to users (or a subscription to service)? Or everyone uses only public domain and open source content for training?

Replies

IMHO (that's not a legal opinion), it is fair use, as long as the images themselves are not included in the app, but just the training result.

I build this opinion on the analogy: a lot of neural networks train by using people faces images ; and for sure they have not asked for individual user permission.