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

4who firstly introduced the idea of a person identification system based on biometric, morphologicaland anthropometric determinations, see [Rho56]. In his effort, Bertillon considered traits likecolors of eye, hair, beard and skin; shape and size of the head, as well as general discriminators likeheight or weight and also indelible marks such as birth marks, scars or tattoos. These descriptorsmainly comprise what is now referred to as the family of soft biometrics, a term first introducedby Jain et al. [JDN04b] to describe the set of characteristics that provide (some) information aboutan individual, but that are not generally sufficient for fully describing and identifying a person,mainly due to the lack of distinctiveness and permanence of such traits. As stated later [JDN04a],such soft biometrics traits can be inexpensive to compute, can be sensed at a distance, do notrequire the cooperation of the surveillance subjects, and can be efficiently used to narrow downa search for an individual from a large set of people. Along the lines of semantic annotation([SGN08] and [RN10]) we here note the human compliance of soft biometrics as a main differencebetween soft biometrics and classical biometrics - a difference that renders soft biometrics suitablefor many applications. The terms light biometrics see in [ALMV04], similes see in [KBBN09]and attributes see in [VFT + 09] have been describing traits we associate to soft biometrics. Thefollowing definition clarifies what is considered here as soft-biometric traits.Definition: Soft biometric traits are physical, behavioral or adhered human characteristics,classifiable in pre–defined human compliant categories. These categories are, unlike in the classicalbiometric case, established and time–proven by human experience with the aim of differentiatingindividuals. In other words soft biometric traits are created in a natural way, used by peopleto characterize other people.Our interest in this thesis is in understanding the role that soft biometrics can play in securityand commercial systems of the future. In brief we begin by specifying soft biometric traits thatadhere to the above definition. After an overview of related work, we proceed to explore differentapplications that benefit from soft biometric systems (SBSs), focusing on surveillance relatedperson identification, and on pruning of large surveillance related searches. We also consider thespecific scenario of applying soft biometrics for human frontal-to-side re-identification. We thenchange gear and deviate from security related applications to the more commercially oriented applicationof employing soft biometrics in quantifying and predicting female facial aesthetics. Theabove approaches are then complemented by a more practical automatic soft biometric classificationtool that we present. Finally, motivated by human acceptance issues, we proceed to provide ausability study relating to soft biometrics.Achievements of the dissertationWe proceed with an explicit description of the scenarios and applications of interest in thethesis.Soft biometrics: characteristics, advantages and related workWe illustrate in Table 1) a range of facial characteristics which accept the definition statedin for soft biometrics. In a first attempt to differentiate between soft biometric traits we firstlyidentify the affiliation to face or accessory categories. We abuse slightly annotation and includehair color in the group of facial soft biometrics. The presented traits list is not exhaustive andwill naturally increase with technological progress.We here note that even though classically accessoriesdo not belong to biometrics, the new stated definition clearly incorporates such traits inthe class of soft biometrics. The motivation for including accessories to soft biometrics lays in theassociated highly descriptiveness and discrimination of attributes such as clothes color, e.g. “the