Velocity and distance of neighbourhood sequences

Das et al. [2] defined the notion of periodic neighbourhood sequences. They also introduced a natural ordering relation for such sequences. Fazekas et al. [4] generalized the concept of neighbourhood sequences, by dropping periodicity. They also extended the ordering to these generalized neighbourhood sequences. The relation has some unpleasant properties (e.g., it is not a complete ordering). In certain applications it can be useful to compare any two neighbourhood sequences. For this purpose, in the present paper we introduce a norm-like concept, called velocity, for neighbourhood sequences. This concept is in very close connection with the natural ordering relation. We also define a metric for neighbourhood sequences, and investigate its properties

Shortest Paths in Triangular Grids with Neighbourhood Sequences

In this paper we analyse some properties of the triangular and hexagonal grids in the 2D digital space. We define distances based on neighbourhood relations that can be introduced in these grids. We present an algorithm, which calculates the distance from an arbitrary point to another one for a given neighbourhood sequence in the triangular grid. Moreover, this algorithm produces a shortest path between these points, as well

Novel Template Ageing Techniques to Minimise the Effect of Ageing in Biometric Systems

ect of ageing on biometric systems and particularly its impact on face recognition systems. Being biological tissue in nature, facial biometric trait undergoes ageing. As a result developing biometric applications for long-term use becomes a particularly challenging task. Despite the rising attention on facial ageing, longitudinal study of face recognition remains an understudied problem in comparison to facial variations due to pose, illumination and expression changes. Regardless of any adopted representation, biometric patterns are always affected by the change in the face appearance due to ageing. In order to overcome this problem either evaluation of the changes in facial appearance over time or template-age transformation-based techniques are recommended. By using a database comprising images acquired over a 5-years period, this thesis explores techniques for recognising face images for identify verification. A detailed investigation analyses the challenges due to ageing with respect to the performance of biometric systems. This study provides a comprehensive analysis looking at both lateral age as well as longitudinal ageing. This thesis also proposes novel approaches for template ageing to compensate the ageing effects for verification purposes. The approach will explore both linear and nonlinear transformation mapping methods. Furthermore, the compound effect of ageing with other variate (such as gender, age group) are systematically analysed. With the implementation of the novel approach, it can be seen that the GAR (Genuine Accept Rate) improved signif