Comment by tlrobinson

Since no one seemed believed it's almost trivial, I went ahead and implemented it:

https://imgur.com/t7ivg0V

It took about an hour of Googling OpenCV questions. Also, I've never actually used OpenCV before, and don't use Python regularly.

I haven't tested it against the full set of images. Even if it's not perfect you could at least use this to narrow down ones that are within some threshold, then manually verify they were tagged correctly.

I'll post the code shortly.