“…The major difference is that the proposed approach separates the non-linear scale-selection and shape-adaptation procedure from the linear anisotropic diffusion scheme, thus bearing closer relationships to the open-ended suggestion in [21] 2 ∇ 2 µ. Algorithmic structure. The general structure of the proposed method resembles the classical structure presented in section I, and used by most classical works on fingerprint image enhancement [3], [8], [9], [10], [11], consisting of an estimation of local image parameters, followed by the application of contextual filters. In this respect, a major difference of the proposed algorithm consists of its iterative coarse to fine structure, where initial coarse estimates lead to a coarsely enhanced image, which is later used to produce more refined estimates and enhanced images, until convergence criteria are achieved.…”