Iris recognizing preprocessing method based on grey level information

Abstract

The invention provides a pretreatment method of iris images based on gray information. A rough circle center (xo, yo) of a pupil is located through binary, mathematical morphology, gray projection and other operations, the point, which has a gray value larger than T and the shortest distance to the (xo, yo), is searched at a plurality of lines close to the (xo, yo) from the center to the two sides as a pupil boundary point; the accurate circle center and the radius of the pupil can be located through curve fitting; the gray level first difference of the lines where the searched pixel points lie is calculated and the point with the largest value of the sum of the level first difference is searched in the range of places where iris external boundary point possibly appears and taken as the iris external boundary point; the accurate circle center and radius of the iris external boundary is obtained after curve fitting. The quality of iris image is judged through calculating point sharpness and number of effective pixel points according to the normalized image. The pretreatment method of iris images of the invention not only can decrease the time needed by repeated iteration during location, but also can judge the quality of iris image accurately and quickly according to the extracted iris image.

Description

technical field [0001] The invention belongs to the technical field of image processing, and mainly relates to iris identification technology in biometric identification. Background technique [0002] In today's information age, how to accurately identify a person's identity and protect information security is a key social problem that must be solved. For this reason, biometric identification technology has quietly emerged, and has become a frontier research topic in the field of information security management in the world. Biometric identification technology refers to the use of the inherent physiological or behavioral characteristics of the human body for personal identification. Iris identification technology is a branch of biometric identification technology. It is the application of computer image processing technology and pattern recognition technology in the field of personal identification. Due to its high stability and high accuracy, it has become a popular develo...

AI Technical Summary

Problems solved by technology

[0010] The above-mentioned iris image preprocessing algorithms all have problems to a certain extent. The positioning algorithm takes a lot of time, and is easily disturbed by the eyelash occlusion problem, and the stability is not high.

Iris image quality assessment method is not universal

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