Fast highly efficient finger print thinning method

A fast, fingerprint technology, applied in instruments, character and pattern recognition, computer parts and other directions, can solve the problems of not single pixel lines, affecting the accuracy of fingerprint recognition, incomplete refinement, etc., to achieve the effect of improving operating efficiency

Inactive Publication Date: 2009-03-11
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention provides a fast and efficient fingerprint thinning method to solve the problems existing in the existing fingerprint thinning method that the thinning is not complete, the thinned lines are not single pixels, and the accuracy of fingerprint identification is affected.

Method used

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  • Fast highly efficient finger print thinning method
  • Fast highly efficient finger print thinning method
  • Fast highly efficient finger print thinning method

Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0008] Specific implementation mode one: this implementation mode consists of the following steps:

[0009] Step A1, fast thinning: first determine the boundary points of the fingerprint lines in the image P to be thinned, and then gradually delete the boundary points of the fingerprint lines to obtain the fast thinning image Q;

[0010] Step A2, OPTA thinning: using the elimination template and the reserved template of the OPTA thinning method, the fast thinning image Q is turned into a single-phase pixel image.

[0011] The method of this embodiment is mainly divided into two parts. The first part is to use the characteristics of the fast thinning method to perform preliminary processing on the image, so as not to directly use the OPTA method to consume more time, and then use the OPTA thinning method to refine the image. The image is thoroughly thinned, which avoids the problem of incomplete image thinning by the fast thinning method, so that the thinned image can better se...

specific Embodiment approach 2

[0012] Specific implementation mode 2: This implementation mode further defines the rapid refinement described in step 1 on the basis of specific implementation mode 1, including the following steps:

[0013] Step B1, construct the following 3×3 neighborhood template for the target point:

[0014] P 8 P 1 P 2 P 7 P 0 P 3 P 6 P 5 P 4

[0015] In the neighborhood of the target point, calculate the number of pixels with a value of 1 in the binarized image N B = Σ i = 1 8 p i and the fraction of connections in the neighborhood T(P 0 );

[0016] Step B2, sequentially scan the image P to be refined, and delete the pixels satisfying the condition TP1 or TP2:

[0017] TP1: center pixel P 0 There are 2-6 eight-connected adjacent pixel points T(P 0 )=1,P 1 P 3 P 5 =...

specific Embodiment approach 3

[0021] Specific implementation mode three: this implementation mode further defines on the basis of specific implementation mode one that the refinement of OPTA described in step one consists of the following steps:

[0022] Step C1, construct the following 16 3×3 elimination templates, where X is an uncertain number, which may be 0 or 1:

[0023]

[0024] Construct the following six 4×4 reserved templates, where X is an uncertain number, which may be 0 or 1:

[0025]

[0026] Construct the following 3 4×4 special templates that need to be discarded among the 6 reserved templates:

[0027]

[0028] Step C2, for the current pixel point Q 0 Extract (from left to right and from top to bottom) 14 adjacent pixels and the current pixel Q 0 Construct the following 4×4 improved OPTA template, where X is an uncertain number, which may be 0 or 1:

[0029] Q 8 Q 1 Q 2 Q 12 Q 7 Q 0 Q 3 Q 13 Q 6 Q 5 Q 4 Q 14 Q 9 Q 10 Q 11 X

...

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Abstract

The invention discloses a fast and effective fingerprint thinning method, which relates to a fingerprint thinning method and aims at solving the problems that the thinning is incomplete, a thinned ridge is not a single pixel, and the correctness in fingerprint recognition can be influenced in the existing fingerprint thinning method. Fast thinning: the judgment is first carried out to boundary points of fingerprint ridges in a picture to be thinned; the boundary points of the fingerprint ridges are gradually deleted to obtain a fast thinning picture. OPTA thinning: a removing template and a preserving template in the OPTA thinning method are utilized for changing the fast thinning picture into a single pixel picture. The invention adopts the combination of the fast thinning algorithm and the OPTA algorithm so as to significantly improve the operational efficiency of the thinning algorithm and solve the problems that a previously-thinned fingerprint picture has more burrs and branch points are incompletely thinned. Meanwhile, the invention can also ensure that the connection of the fingerprint ridges is not damaged; detailed characteristics of the fingerprint are protected; the arithmetic speed is relatively fast; a processed fingerprint picture can be completely thinned and the skeleton can be close to the center line of the fingerprint ridge.

Description

technical field [0001] The invention belongs to a fingerprint identification method, in particular to a fast and efficient fingerprint thinning method, and belongs to the field of fingerprint identification. Background technique [0002] A complete automatic fingerprint identification system (AFIS) mainly includes several modules such as fingerprint collection, fingerprint image preprocessing, fingerprint feature extraction, and fingerprint comparison. Fingerprint image preprocessing is a very important part, its processing effect directly affects subsequent feature extraction and fingerprint comparison, and fingerprint refinement is a very important link in fingerprint preprocessing, because general feature extraction is It is carried out on the basis of refinement. If the refinement is not good, it will not be possible to use conventional feature extraction algorithms to extract feature information of minutiae points. [0003] There are many types of fingerprint refinemen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/00
Inventor 王明江彭刚王进祥闫志锋韦秋初和王峰马晓卫张永胜肖永生董颖杰桑坚张国君刘钊刘鹏
Owner HARBIN INST OF TECH
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