This bot is operated by User:Jonasoberg for the purpose of creating perceptual image hashes of the images on Commons. See Commons-l mailing list mail for the original introductory mail. The bot retrieves new or changed images from Commons and downloads a thumbnail together with associated metadata from the API. It runs a Blockhash algorithm on the file, which is then also recorded.
The blockhash is at the moment only recording this locally to get experience, but it's foreseen that the information will eventually be contributed back to Commons through WikiData.
The bot is written in Python and is fully automatic. It runs on the servers of Commons Machinery