EXTENDED DEPTH-OF-FIELD BIOMETRIC SYSTEM
First Claim
1. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
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IM, comprising;
capturing a raw image of the iris, wherein the raw image has a reduced modulation transfer function (MTF) based on an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM;
normalizing the raw image; and
generating an iris code based on the normalized raw image, comprisingperforming an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image, comprising;
selecting a plurality of bands from the normalized raw image;
processing each of the bands to enhance the MTF; and
fusing the bands to generate the MTF enhanced image; and
generating the iris code from the MTF enhanced image.
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Accused Products
Abstract
An iris recognition system may include an optical system having an intentional amount of spherical aberration that results in an extended depth of field. A raw image of an iris captured by the optical system may be normalized. In some embodiments, the normalized raw image may be processed to enhance the MTF of the normalized iris image. An iris code may be generated from the normalized raw image or the enhanced normalized raw image. The iris code may be compared to known iris codes to determine if there is a match. In some embodiments, the iris code generated by the normalized iris image may be processed with equalization function before comparison with the known iris codes.
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Citations
62 Claims
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1. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
-
IM, comprising;
capturing a raw image of the iris, wherein the raw image has a reduced modulation transfer function (MTF) based on an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM;normalizing the raw image; and generating an iris code based on the normalized raw image, comprising performing an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image, comprising; selecting a plurality of bands from the normalized raw image; processing each of the bands to enhance the MTF; and fusing the bands to generate the MTF enhanced image; and generating the iris code from the MTF enhanced image. - View Dependent Claims (3, 5, 6, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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IM, comprising;
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2. (canceled)
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4. (canceled)
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7. (canceled)
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8. (canceled)
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9. A method of processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
-
IM, comprising;
capturing a raw image of the iris, wherein the raw image has a reduced modulation transfer function (MTF) based on an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM;normalizing the raw image; generating an iris code based on the normalized raw image, wherein generating an iris code based on the normalized raw image comprises generating the iris code directly from the normalized raw image; and generating an equalized iris code based on the iris code and iris code equalization coefficients;
wherein the iris code equalization coefficients have a base function covering a range of spatial frequency bands with related coefficients amplified according to a determined output MTF at related spatial frequencies. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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IM, comprising;
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21. A system for processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
-
IM, comprising;
an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM, the optical system being configured to form on an image sensor a raw image having reduced a modulation transfer function (MTF) based on the spherical aberration;a controller electrically connected to the image sensor, wherein the controller is configured to capture a raw image of the iris, normalize the raw image, and generate an iris code based on the normalized raw image, wherein the controller is configured to perform an MTF enhancement of the normalized raw image in polar coordinates to generate a MTF enhanced image, and generate the iris code from the MTF enhanced image, and wherein the controller is configured to select a plurality of bands from the normalized raw image, process each of the bands to enhance the MTF, and fuse the bands to generate the MTF enhanced image. - View Dependent Claims (23, 25, 26, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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IM, comprising;
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22. (canceled)
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24. (canceled)
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27. (canceled)
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28. (canceled)
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29. A system for processing an extended depth-of-field (EDOF) image of an iris at an imaging wavelength λ
-
IM, comprising;
an optical system having an amount of spherical aberration (SA) of 0.2λ
IM≦
SA≦
2λ
IM, the optical system being configured to form on an image sensor a raw image having reduced a modulation transfer function (MTF) based on the spherical aberration;a controller electrically connected to the image sensor, wherein the controller is configured to capture a raw image of the iris, normalize the raw image, and generate an iris code based on the normalized raw image, wherein the controller is configured to generate the iris code directly from the normalized raw image, wherein the controller is further configured to generate an equalized iris code based on the iris code and iris code equalization coefficients, and wherein the iris code equalization coefficients have a base function covering a range of spatial frequency bands with related coefficients amplified according to a determined output MTF at related spatial frequencies. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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IM, comprising;
Specification