Probably already been thought of:
Provide a repository for photographers to register their images which is capable of detecting similarities via image recognition in cropped images submitted as a search. No need for metadata, which can always be scrubbed. Allows for degraded or partially altered images to still be matched at a lower probability.
Notify both owner and searcher if a probable match is detected so they can each eyeball it for verification.
Subscription required to upload (price based on volume). Free registration for searches, but only for a few per day. Subscription required for larger search volumes.
Business goal is becoming visible enough to become a de facto part of a 'reasonable search'.
Biting the hand that feeds IT
