3.2.3. Definition of Biometric Characteristics

The definition of the biometric characteristics for the verification of bloodstream results originate from the work [20]. For the definition of biometric characteristics in the context of this paper, the similarities of the bloodstream and fingerprints were used. In order to verify a person according to the fingerprints, the comparison of the critical point position (*minutiae*) is used instead of carrying out a comparison of the whole image (on the basis of the sample). For fingerprints' evaluation, the minutiae is used at the beginning and at the end of a dermal papillae, bifurcation (decoupling), hook, and eye. Within this experiment, two types of minutiae were defined, which includes vein branching and vein ending at the top portion of the image. Quantity of located minutiae is expected to be different across all test subjects. However, for one user, the quantity of minutiae located during each scan should be the same. Moreover, the positions of these minutiae in the case of one user should be expected to maintain the same position, no matter the number of scanning. This is because all subsequent images are compared to the image on which the extraction of bloodstream biometric characteristics was done. Therefore, the experimental software works with the minutiae's coordinates, which are closely related to the image of the bloodstream.
