A Systematic Study of Epidermal Ridge Minutiae

Abstract

Abstract To permit the testing of a number of basic hypotheses regarding the relationship between neighboring minutiae, epidermal ridge minutiae on the distal portions of 412 thumbprints have been surveyed. For each thumbprint a centrally located focal minutia was chosen; neighboring minutiae were then sampled. Minutiae were considered to be neighbors if there were no other minutiae in a rectangular region defined by the two minutiae and the ridge system. For each minutia the following data were recorded: minutia type, orientation, ridge count from the focal minutia, and the intervening distance along the ridge flow. The number of neighbor minutiae was found to be normally distributed. Minutia orientation frequencies on the right and left hands were found to be unequal and to show a mirror image relationship. The incidence of particular minutia orientations and types were found to vary with ridge count from the focal minutia. Linear descriptions of these relationships were found to be adequate after adjustments were made for geometrical restrictions present for ridge counts of one, zero, and negative one. Predicted frequencies of minutia types and orientations for each ridge count were found to be in acceptable agreement with the observed frequencies.