Only 109 retrievable images out of the 350,000 most-duplicated is fewer than I expected. Maybe it's just the stringent definition of retrieval, but I would have

Only 109 retrievable images out of the 350,000 most-duplicated is fewer than I expected. Maybe it's just the stringent definition of retrieval, but I would have expected many famous works of art like the Mona Lisa and Girl with a Pearl Earring to be readily extractable. Maybe these just aren't quite pixel-perfect enough?