FACIAL SOFT BIOMETRICS - Library of Ph.D. Theses | EURASIP

95Table 8.1: User experience on access methods.Soft Biometrics Face PIN Fingerprint0/15 2/15 15/15 12/15camera capturing, fingerprint scanning and PIN entry. All four interfaces initially asked for theentry of the username. In the following the methods differed as they acquire the following diverseinformation:Soft biometrics, denoted as SB : For the soft biometric based authentication method the useris captured by the laptop integrated webcam and weak biometric facial classifiers including age,gender, hair and skin color are extracted. He / she can unconstrained capture his / her face bypressing a button. An indicator in the related window describes the one-by-one processing of eachtrait.Face, denoted as Face : Similar to soft biometrics, in the face based system the face of theuser is captured, but he / she is asked to place their face in a pre-defined blue elliptical mark. Thisconstraint is originally designed in order to differentiate the first two access methods. Furthermoreit indicates the common pose-constrain of face recognition.PIN, denoted as PIN : Additionally to the username for the PIN based verification a five-digitpassword was requested, along with a button confirmation for a successful verification.Fingerprint, denoted as FP : In this access method a scanner acquired the user fingerprint dataof the index finger of the left hand. To initiate the scanning process the user had to press theconfirm button. The processing time of all systems, indicated by progressing bars, was designedto be very similar in order not to affect the user preference.8.2 User study related resultsFirstly we inquired previous experience of users on the presented access methods, see Table8.1. All users employ PIN based verification system daily, on personal computers, ATMs,mobile phones or web pages. This fact can be biasing on the one hand towards PIN, on the otherhand it accelerates the awareness of related drawbacks. Surprisingly the majority of user hadprevious experience with fingerprint based verification systems incorporated in personal laptopsor for border control. Soft biometrics was a novel technique to all subjects, whereas face basedverification was used before by two users.Then we proceeded with the questions about usability related measures in context of the differentmethods.8.2.1 Ease of access, user friendliness, time to acquire and clarityThe first graph in Figure 8.2 reflects on how intuitive users found the system. All methodsprovide according to the users an intuitive access, but soft biometrics was significantly best re-