Used to be able to find a movie screenshot on Tumblr, image search it and the name of the movie would come up.
The current system seems to use machine learning to try and tell what the content of the image image is then just provide generic results for that term along with a similar color palette. Google Image Search used to be perfect, around 2-4 years ago or so they swapped out the old school system which seemed to take some sort of fingerprint of the image and then tell what it was from the context of pages the image was found on.
