1. A fingerprint sensing apparatus, comprising: a fingerprint sensor system; and a control system of configured for: receiving fingerprint sensor data from the fingerprint sensor system, wherein the fingerprint sensor data are data received from fingerprint sensor pixels of the fingerprint sensor system; determining fingerprint sensor data blocks for at least a portion of the fingerprint sensor data, wherein the fingerprint sensor data blocks correspond to blocks of fingerprint sensor pixels of the fingerprint sensor system; calculating characteristics of variability for fingerprint sensor data corresponding to each of the fingerprint sensor data blocks; determining, according to the characteristics of variability, whether an object is positioned proximate a portion of the fingerprint sensor system, wherein determining whether an object is positioned proximate a portion of the fingerprint sensor system involves determining whether the characteristics of variability are above or below a threshold value; and determining, according to whether an object is positioned proximate a portion of the fingerprint sensor system, whether to terminate processing of the fingerprint sensor data.