Estimation of the directional field anisotropy based on Mohr´s Circle in fingerprint images

Traditional gradient based methods are used for the estimation of directional field anisotropy and the associated values called coherence/strength that denote the consistency of the orientation. Using a geometric interpretation of Mohr´s Circle, a new method is proposed to estimate the directional field anisotropy and a new indicator called uniformity is introduced. Starting from the autocovariance 2×2 symmetric matrix, eigenvalues are computed and yield the new measure for anisotropy.