Image analysis – Applications – Personnel identification
Reexamination Certificate
1999-07-09
2003-02-25
Werner, Brian (Department: 2621)
Image analysis
Applications
Personnel identification
C382S324000
Reexamination Certificate
active
06526160
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an iris information acquisition apparatus, an iris identification apparatus and the others, and particularly to techniques capable of remarkably reducing time from an image pickup of an iris image to generation of an iris code, and capable of simplifying the iris information acquisition apparatus, the iris identification apparatus and the like.
BACKGROUND OF THE INVENTION
Security systems accompanying development of high computerization in recent years require high reliability and convenience. In these security systems, for example, key, password, ID card, IC card, signature, voiceprints, fingerprints, biometric features (face pattern, set of teeth, retina, iris pattern and so on) are used as recognition means. Generally, in order of description of the above recognition means, degree of problems that these recognition means must be carried, are forgotten, are difficult to operate, are lost, are forged, etc. decreases, with the result that the recognition means have high reliability while the security systems become complicated and expensive.
The fingerprints among the above recognition means have been adopted by the police etc. of the whole world in the past and have been the most familiar personal identification means. However, a pattern of the fingerprints at the time of registration is not identical with that of the fingerprints at the time of matching since the fingertips are soft, and also, a false acceptance rate which is a probability of deciding the patterns identical in spite of the different patterns of the fingerprints and a false rejection rate which is a probability of deciding the patterns different in spite of the identical patterns of the fingerprints are said to become about 10 to 20% since the fingerprints themselves are easy to transform.
Also, in a system for matching a blood vessel pattern on the retina, to detect this blood vessel pattern, behavior of looking through a device for detecting the blood vessel pattern is forced and the false rejection rate becomes high due to influence of retinitis (hemorrhage of fundus oculi, white patch, exudation) and so on.
On the contrary, the iris pattern which has a demerit of hiding the iris in an eyelid is said to be almost immutable until death since two years of age, and a personal identification rate using the iris pattern has high reliability and thus, the iris pattern is said to be the most excellent personal identification system. As shown in
FIG. 15
, the iris means a region
101
having a pattern drawn radially on the outside of a pupil
100
.
The personal identification system using such the iris pattern is disclosed in U.S. Pat. No. 5,291,560, for example. Also, an “IrisIdent” (registered trademark) system made of SENSAR Inc. in the U.S.A. is used as a practical system. As shown in
FIG. 16
, this system roughly comprises two illumination parts
110
, a camera part
111
, a processing part
112
, and cables
113
for connecting the camera part
111
to the processing part
112
. And then, the processing part
112
is connected to a host computer (not shown). A personal recognition processing using the system is generally performed according to the following procedure.
First, a three-dimensional position of the eye of human locating at the front of the camera part
111
is calculated on the basis of stereoscopic vision by two wide-angle cameras in the camera part
111
. This calculation is performed by the processing part
112
on the basis of image pickup information fed from the wide-angle cameras.
Secondly, a zoom camera in the camera part
111
is focused on the three-dimensional position fed from the processing part
112
and zoom magnification is inversely proportioned to the distance.
Thirdly, by this, an iris image caught by the zoom camera is taken with a CCD image sensor of said zoom camera and is fed to the processing part
112
.
Fourthly, the processing part
112
divides an iris portion (a region from the inner boundary to the outer boundary of the iris) in the taken iris image into eight concentric bands so as not to be influenced by variations in the pupil diameter. This is because the inside of the iris portion stretches and contracts in response to change in the pupil and thus the iris pattern itself stretches and shrinks. But, the outside of the iris portion does not change.
Fifthly, a convolution operation using a two-dimensional Gabor filter for feature extraction is performed every the divided band and a band-pass filtering is performed and the result is formed in binary code.
Sixthly, an iris code of 256 bits is calculated from the obtained binary information every the band.
Lastly, The processing part
112
performs personal identification by deciding whether the calculated iris code is matched with the previously registered iris code or not. This personal identification may be performed through the host computer (not shown) connected to the processing part
112
.
In the personal identification system using the iris pattern mentioned above, however, the normal CCD image sensor arranged in a grid shape is used when the iris image is acquired, so that a coordinate of the iris portion of the iris image taken by the CCD image sensor must be transformed from an orthogonal coordinate system to a polar coordinate system and further, the convolution operation to each the transformed band must be performed. Since it takes an enormous time to process the coordinate transformation or the convolution operation, the is personal identification system had a problem that such the coordinate transformation or the convolution operation greatly affects a delay in processing time of the whole identification processing.
Although the above problem may be solved by enhancing the calculation capability of the processing part
112
, a new problem has arisen in that the enhancement of the calculation capability requires a high cost naturally, and obstructs miniaturization and weight-saving of the personal identification system including the processing part
112
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an iris recognition and identification method and its system capable of removing the above-mentioned problems of the prior art.
It is another object of the present invention to provide an iris recognition and identification method and its system capable of remarkably reducing time required from image: pickup of an iris image to generation of an iris code as well as of simplifying the system.
It is yet another object of the present invention to provide an iris recognition and identification method and its system capable of remarkably reducing time required from image pickup of an iris image to generation of an iris code and further capable of simplifying the system.
According to an aspect of the present invention, there is provided an iris information sensor comprising an image pickup sensor having a group of photoelectric conversion pixels arranged in polar coordinates, wherein image light from an iris region of an eye is focused on the image pickup sensor so that the center of an iris image formed on the sensor substantially matches with the pole of the polar coordinates of the sensor and the photoelectric conversion pixels of the sensor are sequentially scanned to read out an iris image signal.
The image pickup sensor may be made of a group of pixels arranged in concentric circles.
The image pickup sensor may also be made of a group of pixels arranged in a spiral shape extending in the radial direction.
According to another aspect of the present invention, there is provided an iris information acquisition apparatus for obtaining image information of an iris region, comprising:
an image pickup sensor having a group of photoelectric conversion pixels arranged in polar coordinates;
image pickup optical system means for focusing image light from the iris region on the image pickup sensor;
optical axis operation control means for matching the center of an iris image formed on the sensor with the pole of the
Greenblum & Bernstein P.L.C.
Media Technology Corporation
Werner Brian
LandOfFree
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