Fingerprint image orientation enhancement method

Abstract

The invention relates to the field of fingerprint image processing, in particular to a fingerprint image orientation enhancement method. The technical proposal adopted in the invention comprises the following steps of: 1) adding a step of Gabor pre-filtering, adjusting filtering parameters again after conducting preliminary directional filtering enhancement on the original image, and conducting secondary accurate Gabor filtering; and 2) adopting a self-adaptive measure of a Gabor filter transmission band to calculate respective numerical characteristics of the original fingerprint image and the pre-filtered fingerprint image and dynamically adjust the width of the filter transmission band. The fingerprint image orientation enhancement method has the beneficial effects: 1) the method improves the defects of the prior art that filtering is only implemented for once, the filtering parameter is an fixed experience value, and the filtering effect is too rough; 2) fingerprint ridges obviously separate, the edges of the ridges are smooth, the noise points are removed from the fingerprint ridges, and the original features such as scar and the like are kept simultaneously; and 3) compared with the prior art, the uniformity and definition of the fingerprint ridges, the capability of recovering the broken ridges and the like are remarkably improved.

Description

technical field [0001] The invention relates to the field of fingerprint image processing; in particular, it relates to a fingerprint image direction enhancement method. Background technique [0002] Fingerprints are made up of alternating ridges and valleys. In an ideal fingerprint image, the ridges and valleys are uniform in thickness. Except for individual areas such as minutiae and singular points, the ridges and valleys in most areas are parallel to each other and evenly spaced, presenting a continuous curve with a gentle change in direction. . When the fingerprint image is taken, due to various reasons, the fingerprint image cannot reach the above ideal state. It is necessary to use fingerprint image enhancement technology to eliminate noise, enhance the effective information in the original collected fingerprint image, and restore the real and clear fingerprint. The ridge structure achieves the effect of improving image quality. [0003] In digital image processing...

AI Technical Summary

Problems solved by technology

[0006] However, the existing method of using Gabor filtering for fingerprints still has problems in the technical effect of direction enhancement, mainly in that the existing fingerprint image preprocessing only uses one-time Gabor filtering, and the filtering effect is too rough; The setting of ξ (equal to the reciprocal of the filter Gaussian envelope space constant δ) is a fixed empirical value based on the assumption that the quality of the fingerprint image is in an ideal state

In practical applications, if you encounter a fingerprint image in a non-ideal state, for example, if your finger is too dry to break the pattern of the fingerprint image, or if your finger is too wet to make the pattern of the fingerprint image stick, you need to dynamically adjust the value of δ and change the value of the filter passband ξ In order to adapt to the filtering requirements of different fingerprint image quality characteristics, the existing fingerprint filter enhancement technology has obvious shortcomings in terms of adaptability and fingerprint enhancement effect.

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