Soft biometrics

Soft Biometrics traits are physical, behavioural or adhered human characteristics, classifiable in pre–defined human compliant categories. These categories are, unlike in the classical biometric case, established and time–proven by humans with the aim of differentiating individuals. In other words the soft biometric traits instances are created in a natural way, used by humans to distinguish their peers.

Introduction

The beginnings of Soft Biometrics can be identified as laid by Alphonse Bertillon in the 19th century. He firstly proposed a personal identification system based on biometric, morphological and anthropometric determinations . The most common traits he introduced were colour of eye, hair, beard and skin; shape and size of the head; body characteristics like height or weight and also description of indelible marks such as birth marks, scars or tattoos. A great majority of those descriptors fall at the present time into the category of Soft Biometrics.

Jain lately rediscovered Soft Biometrics as a set of traits providing information about an individual, though these are not able to individually authenticate the subject because they lack distinctiveness and permanence

Soft Biometrics examples

Traits which accept the above definition include, but are not limited to:

• Physical: skin colour, eye colour, hair colour, presence of beard, presence of moustache, height, weight.
• Behavioural: gait, keystroke.
• Adhered human characteristics: clothes colour, tattoos, accessories.

Soft Biometrics inherit a main part of the advantages of Biometrics and furthermore endorses by its own assets. Some of the advantages include non obtrusiveness, the computational and time efficiency and human compliance. Furthermore they do not require enrolment, nor the consent or the cooperation of the observed subject.