The present disclosure relates to a method of determining that a finger covers a sensor area of a fingerprint sensor. The method comprises, on a surface of the fingerprint sensor, receiving a finger having a fingerprint topography. The method also comprises, by means of the fingerprint sensor, acquiring an image of the fingerprint of the received finger. The method also comprises dividing an image area (41)of the acquired image, corresponding to the sensor area of the fingerprint sensor, into a plurality of image regions (r), said regions partly overlapping each other and covering the whole image area. The method also comprises, based on image analysis of each of the plurality of image regions, determining that the finger covers the whole sensor area.
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