If the threshold is 4, then 4 photos needed to have incorrectly matched, meaning the accuracy needs to only be 1/10000 if the average user has 10k images. (1/10

If the threshold is 4, then 4 photos needed to have incorrectly matched, meaning the accuracy needs to only be 1/10000 if the average user has 10k images. (1/10000)^4*10k is 1 trillion.