On the Extent of Longitudinal Finger Rotation in Publicly Available Finger Vein Data Sets

Finger vein recognition deals with the identification of a subjects based on its venous pattern within the fingers. The majority of the publicly available finger vein data sets has been acquired with the help of scanner devices that capture a single finger from the palmar side using light transmission. Some of them are equipped with a contact surface or other structures to support in finger placement. However, these means are not able to prevent all possible types of finger misplacements, in particular longitudinal finger rotation can not be averted. It has been shown that this type of finger rotation results in a non-linear deformation of the vein structure, causing severe problems to finger vein recognition systems. So far it is not known if and to which extent this longitudinal finger rotation is present in publicly available finger vein data sets. This paper evaluates the presence of longitudinal finger rotation and its extent in four publicly available finger vein data sets and provides the estimated rotation angles to the scientific public. This additional information will increase the value of the evaluated data sets. To verify the correctness of the estimated rotation angles, we furthermore demonstrate that employing a simple rotation correction, using those rotation angles, improves the recognition performance.