Touch ID takes a 88x88 500ppi scan of your finger and temporarily sends that data to a secure cache located near the RAM, after the data is vectorized and forwarded to the secure enclave located on the top left of the A7 near the M7 processor it is immediately discarded after processing. The fingerprint scanner uses subdermal ridge flows (inner layer of skin) to prevent loss of accuracy if you were to have micro cuts or debris on your finger.
read more.....https://www.schneier.com/blog/archives/2014/04/details_of_appl.html
read more.....https://www.schneier.com/blog/archives/2014/04/details_of_appl.html