1. An image processing system comprising: a digital data store storing a first image and a second image; a computer processor coupled to the data store and programmed to: generate a first fingerprint of the first image based on a first plurality of pixels from the first image stored in the data store; generate a second fingerprint of the second image based on a second plurality of pixels from the second image stored in the data store; determine a closeness value between the first fingerprint and the second fingerprint; determine, based on the closeness value, whether the first image matches the second image.