Copies that were freely shared for the purpose of letting anyone look at them.
Do you think it's copyright infringement to go to a website?
Typically, ephemeral copies that aren't kept for a substantial period of time aren't considered copyright violations, otherwise viewing a website would be a copyright violation for every image appearing on that site.
Downloading a freely published image to run an algorithm on it and then deleting it without distribution is basically the canonical example of ephemeral.