If you're looking for posted Bitcoin addresses, it's quite easy to find. If you have to get the information from images, I don't know how to automate that.
I think that could be pretty easy to automate, you would need some tricks for distinguishing keys from other numbers like dates and block heights and stuff people put in photos. The biggest issue would probably be cost....because the keys are usually small relative to the picture, the Cloud API probably wouldn't work, although I'll check to see. You would have to run a custom algorithm that zooms in on the coin....doable, but probably very expensive to do in the cloud.
The first step would probably be to do a quick and dirty scrape and see how many were missing addresses, and go from there. This shit will only get easier and cheaper to do though, the stuff you can do with AWS now is lightyears ahead of where they where even a year ago.
https://docs.aws.amazon.com/rekognition/latest/dg/detect-labels-console.html