1. A method in a biometric sensing system of authenticating a user using a body part including biometric information, the method comprising: stitching partial enrolment images comprising different views of the user's body part into one or more mosaics and thereby creating an enrolled image, acquiring an authentication image of the body part, wherein the size of the authentication image is a fraction of the enrolled image, determining at least one area of interest in the enrolled image by comparing features in the authentication image with features in the enrolled image, and wherein a difference in size between the area of interest and the area of the authentication image is below a tolerance value, and matching the authentication image with image data of the determined area of interest in the enrolled image, and thereby enabling authentication of the user.