An apparatus and a computer-implemented method of acquiring a fingerprint image from a fingerprint sensor with an array of sensor elements spanning a sensing area, comprising: monitoring groups of sensor elements located at group-wise spaced apart positions in the array of sensor elements, to determine a touch event occurring on the array of sensor elements; from the array of sensor elements, acquiring, at respective points in time, fingerprint sub-images which are confined in size to a subarea of the sensing area; as the fingerprint sub-images are acquired, computing values of a statistical indicator for the fingerprint sub-images; and acquiring a full fingerprint image when a predefined criterion indicates that the values of the statistical indicator has reached or is about to reach a stable state.