1. A computer implemented method comprising: acquiring digital image data representing an image of at least a portion of a physical object that belongs to a class of objects; accessing a predetermined object feature template associated with the class of objects, the feature template identifying a plurality of individual authentication regions; processing at least portions of the digital image data corresponding to the identified authentication regions so as to form a digital fingerprint of the object, wherein the processing comprises the following steps— extracting at least one object feature to characterize the image data in each of the authentication regions; for each of the extracted object features, forming at least one fingerprint feature vector that describes the object feature extracted from the image data; and storing the fingerprint feature vectors of the object in an object database as part of a digital fingerprint of the object.